The Training Montage. It's cool seeing Sherman being more athletic and competent.
Even more awesome: he does it in less than a week.
Buddy Love getting back at Reggie for the way he treated Sherman.
When Richmond starts coming down on Buddy for being late to the party, Buddy screams at him to "SHUT UP", he's sick of him, doesn't care what he says, and tells him he'll kill him in front of everyone if he doesn't back off. Richmond was more than surprised at his sudden outburst.
The fact that Eddie Murphy plays the ENTIRE Klump family and is unrecognizable. Also, he sat 4 to 5 hours to play all of them. Not only that, he plays Lance Perkins, a white Richard Simmons Expy.
When Sherman is fighting Buddy, Buddy yells "SHERMAN, YOU CAN'T BEAT ME!" Buddy turns back into Sherman and yells "YES, I CAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAANNNNNNNN!!!" Sherman eventually wins the fight. Also doubles as a nice Call-Back to earlier scenes, and a CMOH.
Sherman tricking Buddy into drinking the formula. And Sherman thought up this just when his intelligence is almost non-existent.