(In Shakespeare's time, the biting of one's thumb is considered an insult, roughly an equivalent of giving someone the middle finger. Thumb biting is also what starts the fighting between the two families in Shakespeare’s play, "Romeo and Juliet". Shakespeare uses this gesture to let Seuss know who and what he's dealing with.)
I'll put a slug between your shoulder blades!
("Slug" here refers to a bullet slug. Shakespeare will shoot Seuss between his shoulder blades, or the head.)
Then ask what light through yonder poser breaks?
(After shooting Seuss, Shakespeare will marvel at the light passing through the bullet hole in Seuss's body. It is also a reference to a line in "Romeo and Juliet".)
I hath been iambic on that ass, ye bastard.
(Shakespeare writes his rhymes on an iambic pentameter, a rare and classic meter in rapping. Iambic pentameter involves a ten syllable line, with five unstressed syllables and five stressed syllables, and he counts each with his fingers on his hand, saying he'll use all five fingers to whup Seuss's ass. Shakespeare used iambic pentameter in the three previous lines. This line is also technically iambic hexameter, in that is has 6 iambi (12 syllables) instead of 5.)
My rhymes are classic. Your crap is drafted by a kindergartner high on acid!
(Shakespeare's works are original and timeless. Seuss's works are simplistic and seem to be drawn by a little kid who has taken too much hallucinogens.)
Ye hoebag, you're an old, white, Soulja Boy who has no swag,
(Seuss is an aged Caucasian. Soulja Boy is widely derided for his lack of lyrical and technical ability, but he does have "swag". Seuss has none of those. This may also be pun as Dr. Seuss is known for having served in the army. Incidentally, Shakespeare also invented the word "swag". Specifically, he invented the word "swagger", from which "swag" is derived. Midsummer Night’s Dream contains the first recorded instance of the word.)
And no gonads. Egads, it's so sad!
(The gonads are the organs that store gametes. Shakespeare is saying that Seuss doesn't have testicles. Egads is another old-timey word expressing one's surprise. Shakespeare is surprised at how weak Seuss appears to be.)
And to top it off, you're not a doctor.
(Dr. Seuss is actually just an alias used by Seuss. He is not an actual doctor, though his parents wished he became one.)
I've never seen a softer author.
(To call someone a "soft rapper" means to call them a poser, so calling Seuss a soft author means he's only a wannabe author, and his literary work lacks substance. Seuss's works are mostly designed for children, even though he is also a political cartoonist.)
You crook, you. I bet you wrote the Twilight books, too!
(Twilight books are widely regarded as one of the worst book series of all time. Shakespeare says Seuss' work is a fraud, and it's so bad, he may have even written the entire Twilight series. Ironically, the author of the series, Stephenie Meyer, says that she drew inspiration for the books from some of Shakespeare's plays.)
(This is a line from Dr. Seuss' book "Green Eggs and Ham", in which Sam I Am offers a character some green eggs and ham, and the character responds saying that he would not, could not eat them on a boat, as well as several other places.)
Read any of the boring ass plays you wrote.
(The Cat in the Hat wouldn't want to read Shakespeare's plays because they are considered to be very elongated and boring.)
Even Horton doesn't want to hear you.
(Horton the Elephant is one of Dr. Seuss's characters from the book "Horton Hears A Who". He heard a speck of dust talking to him, which was really a small planet inhabited by the Whos in Whoville. Horton was the most compasionate in his story and the only character of his book who was interested in what the Whos had to say, however even Horton wouldn't want to hear Shakespeare.)
And Cindy Lou Who is afraid to go near you!
(One of the aforementioned Whos is named Cindy Lou Who, who is the only Who that approached the Grinch in Seuss' book "How The Grinch Stole Christmas". If she would go near the Grinch but be scared of Shakespeare, he must be really bad.)
You bore people to death!
(Shakespeare's plays are normally read in high-school classes, and they are so long that it easily becomes uninteresting.)
You leave a classroom looking like the end of Macbeth!
(Macbeth, one of Shakespeare's plays, has almost every main character die by the end, so nearly, if not completely every classmate reading his plays dies of boredom.)
I entertain a child of any age.
(Cat in the Hat, and to an extent, Dr. Seuss, leaves children entertained, as well as an older audience.)
You gotta translate what you said on the opposite page!
(Shakespeare used Early Modern English in his works. As such, many words and phrases he used are difficult to understand because they've been unused, so many modern printings of his works have the original on the left page and a translation on the right page, as you hold it open.)
How are you gonna battle with the Cat in the Hat?
(The Cat says Shakespeare doesn't have a chance against him.)
Little kids get scared when I step on the mat.
(The Cat in the Hat was known for his mischievous manner, so when he enters the house, normally stepping on the mat, the kids know he'll be causing trouble.)
You think your ruffled neck ass gonna rap to that?
(Ruffled necks are a famous piece of fashion in Shakespeare's time. The Cat thinks someone wearing something as ridiculous as that can't beat him in a rap battle.)
I got a best selling book about me coming back!
(The Cat in the Hat had a second book, appropriately named "The Cat in the Hat Comes Back". It may have been his most popular book.)
I'm switching up my style like the Beatles with my pieces.
(The Beatles are widely regarded as one of the best bands ever. Shakespeare is saying that he's in the same level in literature as the Beatles are in music, and that he will change the style of his works, like the Beatles did with their songs, as Shakespeare was known for writing various genres of stories, while Seuss normally wrote one style. He also switches up his style in terms of changing from iambic meter to unbelievably rapid rhyming.)
Each is such a wonder with a plethora of features.
(Each and every one of Shakespeare's plays are a wonder with lots of features and gimmicks in it compared to Seuss'.)
You're pathetically predictable.
(Shakespeare is saying that Dr. Seuss is so repetitive that it's easy to conclude what happens next, so his imagination isn't anything new. He is also saying that Dr. Seuss gives away spoiler alerts.)
You think your new book might include a trisyllabic meter and some ghetto Muppet creatures.
(Dr. Seuss' books are written in a trisyllabic meter, and usually includes drawings of the characters involved. Shakespeare is saying the characters look like strange Muppets. Also, there was a show called The Wubbulous World of Dr. Seuss with puppets of Dr. Seuss' characters from The Jim Henson Company.)
The Bard is in the building. It's a castle, I'm the boss.
(Shakespeare's nickname is "The Bard of Avon". He says he's in the house, which in English terms, would be the castle, and he's the boss, or ruler, of said castle.)
I bet I'm parliament. I'm positive, I'm killing it.
(Some of Dr. Seuss's books are political and try to bring down parliament, which is the British legislature, whereas parliaments are difficult to be brought down. Shakespeare is saying that he's sure he's more powerful than parliament and Dr. Seuss can't bring him down.)
I'm iller than the plague. I've never caught a cholera.
(Shakespeare's rhymes are deadlier than the Black Plague, a famous disease that killed millions of people during his era. He also never caught the pandemics that happened in his time, so he claims that his rhymes are sicker than the plague.)
A baller baller, on some cricket bowler business while you're sitting in the bleachers!
(A baller is usually someone who's big and famous, in this case, Shakespeare. It can also refer someone who has balls, which also implies to Shakespeare. Cricket is a sport similar to baseball which is normally played in European countries. The bowler is the one who pitches the ball towards the batsman, so Shakespeare would be the one to be the star player, metaphorically, and Dr. Seuss is only watching from the sidelines.)
Cat in the Hat:
You rap fast, you do. Yes, you rap fast, it's true.
(Shakespeare's last line was delivered very speedily.)
Now let's see how you rap versus Things One and Two!
(The Globe was a theater made for Shakespeare and his plays, and Things 1 & 2 are going to trash it.)
Yo, you may have wrote the script, but now we running the show!
(While Shakespeare may have written the script for the play, it is the actors that run the show. Things 1 & 2 are presumably going to be the ones to take charge now.)
You can take your fancy words and send 'em back home to your mama.
(Shakespeare made up words, like "puke", "eyeball", and "cater". The Things tell him his fancy language should be sent back home to his mother.)
Break our foot off in your ass, with our feetie pajamas.
(Things 1 & 2 wear feetie pajamas, and they're going to kick Shakespeare's ass with them.)
Man, we'll cook you up and eat you with some ham and green eggs!
("Green Eggs and Ham" is the name of a Dr. Seuss book. The Things will cook Shakespeare up with them.)
We'll break offa your legs, make no mistake, we in a rage.
(Things 1 & 2 will rip off Shakespeare's legs. Their usual behavior makes them look like they're in a rage.)
All does not end well when we bust out our cage.
("All's Well That Ends Well" is the title of one of Shakespeare's plays, and Things One and Two are kept in a cage as to avoid them creating havoc, which they will do now that they're let out, so it will not end well anymore for Shakespeare.)
You're getting upstaged, Bill. Yo, you just got played!
(The Things call William Shakespeare "Bill", since "Bill" is a short form of the name William. Upstaged is a term when an actor is eclipsed by another (presumably better) actor. The last line is a play on words, namely "PLAYed", as Shakespeare was a playwright. "To have been played" means that a person has been tricked or has otherwise been taken advantage of by the "player".)