Acting for Two: In the original, Jerry Lewis plays the lead, which is sort of two separate characters who happen to share a body that changes a little between the two of them.
In the 1996 film, Eddie Murphy plays the lead. He also plays the alternate persona. And a white celebrity fitness instructor... And his entire family (barring one child and one of the two grandparents).
The sequel was actually called The Klumps, making Eddie Murphy's scenes with one actress and several of his own characters into the core of the film.
Amazingly Embarrassing Parents: The Klumps when Sherman brings Carla over. They talk openly about sex, bodily functions, marriage, and other embarrassing topics, so much so that Sherman tries to slit his wrists with a butter knife.
An Aesop: Be yourself. Don't try to be someone else to win others' affections.
Ascended Extra: Sherman's parents in the remake. The original film, they only appear twice, the first time shown as a henpecked guy and his mercilessly henpecking wife, and the second at the end where They come to sell the serum to all the kids in school. In the remake, they appear far more often, and get along quite well with each other.
Darker and Edgier: The Klumps had a few moments of that range from dark humor to horror. Buddy Love in the second movie is more evil than he ever was in the first nor its predecessor. Going from trying to take Sherman's place to downright trying to stalk and destroy Sherman and anyone else that got in the way. Even before his DNA was separated from Sherman's he even found many ways attacking him on the inside. From giving him a terrible nightmare to alienating him from his father and love interest. That aside there were Tear Jerker moments too, from relationship problems between Sherman's parents mirroring Sherman's relationship with Denise, as well as breaking off the marriage under the belief that he can't be a good husband after his intellect is deteriorating, especially due to an incident where Buddy Love sabotaged the fountain of youth formula and stole the actual sample, causing a test gone awry. The audience was also almost fooled with a Bittersweet Ending, when we including Denise and Cletus thought Sherman was brain dead for good.
It's Not You, It's Me: Sherman Klump ends up breaking off the marriage because he believes that he can't be a good husband while his intellect was deteriorating after removing Buddy Love from his system.
Mean Boss / Dean Bitterman: Richmond, the dean of the university that Sherman Klump works at, frequently insults Sherman Klump's obesity and makes no secret of his contempt of Klump.
Jerk with a Heart of Gold: Despite this, he did ally with Sherman Klump to stop Buddy Love from stealing the patent for the fountain of youth formula in the climax of The Klumps.
Meaningful Echo: Buddy to Dean Richmond: "Who you think you talkin' to, Sherman Klump? Man, if you ever talk to me like that again, I'll kill you. And I don't mean it as euphemism, I'm gonna literally kill you. I'm gonna strangle you and cut off your air supply until you pass away."
Meaningful Name: The fact that the last name of the universally overweight Klumps sounds like plump is obvious. More so is that the slender love interest in the 2nd film is named 'Gains', especially when we're shown that Mrs. Klump's old wedding dress fits her.
You won't. I know you won't. As a matter of fact, I know you're going to be perfect! Do you know how I know all these things? I know them because if you're *not* perfect, nevermind the yelling, the screaming and the firing. If anything goes wrong, for any reason...I'm going to kill you. And I don't mean that as a euphemism, I am going to literally kill you. I'm going to strangle you and choke off your air supply until you pass away.
Oh Crap: Sherman in the first film when he wakes up next to three hookers after a night of partying (as Buddy).
Sexier Alter Ego - In both versions, the titular professor invents a way to change him from a nerdy looking fellow in the original film (and a rather overweight guy in the remake) into a smooth ladies man.
Sexual Karma: The Jerk Ass dean gets more than his share of this, courtesy of "Jumbo the Horny Hamster".
Squirrels in My Pants: Variation: During a demonstration test on the fountain of youth serum on a hamster, it initially works, but thanks to Buddy Love sabotaging the serum earlier, the hamster ends up basically turning Godzilla on them, forcing the audience to evacuate and the guards to fire on "hamsterzilla" before it dispatched them with turds. It then sees Dean Richmond (wearing a fur rug over himself in a failed attempt to hide) and, mistaking Richmond for a potential mate, gets very interested in him and is also strongly implied to have raped him. As the cameras were still rolling, this was also shown on TV across the state, if not the nation or the world, as the scene in the Klumps' living room revealed.
It happened even earlier in the first film. Klump had accidentally let loose all the hamsters on the campus. one climbed into a student's pant legs. The girl he was talking to clearly mistook it as something else.
Stealth Pun: The theater scene in the sequel. The original Nutty Professor was made a year after Cape Fear, whilst in the remake's sequel, Buddy is laughing mad while watching the original in the style of De Niro's Max Cady's Iconic scene in the remake of Cape Fear.
Synchronized Swarming: In the 1990s film, the professor proposes to his girlfriend by attracting fireflies into the words "Marry me?" using a synthesized firefly pheromone.
Take That: Eddie Murphy's Buddy Love sent up the negative traits of his own persona during his cold streak at the box office, something that did not go unnoticed by critics.
Jerry Lewis' Buddy Love has been interpreted as a parody of Dean Martin, Lewis' old show business partner, although Lewis has repeatedly denied this.
That Came Out Wrong: "Pardon me ladies and gentlemen, but I cannot go on living unless I have this man inside me right now!"
The Triple: Dean Richmond being a jerk to Sherman at the start of the movie.
Dean Richmond: Can I get you anything? Juice? Coffee? Rack of lamb?
This Ain't Rocket Surgery: In the 1990s film, Sherman, whose mind is decaying rapidly and is just about to meet Denise's parents, assures himself that he won't make a fool of himself because Denise's parents are probably not rocket scientists. Turns out that's exactly what they are.
Toilet Humor: The 1990s movie has a lot of fart jokes, as well as implied soiled pants.