"I get to cut you oooppeeen, I get to cut you ooopeeen!"
http://www.youtube.com/watch?v=AsJFpzETgOg

Turk rewrites Sandford and Son theme song (someone else posted it up top already)
http://www.youtube.com/watch?v=XwsZOkdlqIw

Turk and JD sing the Sanford and Son theme song (this predates Turk rewriting it by about 3 seasons)
http://www.youtube.com/watch?v=j8obUzlq3Ww&feature=related

Dr. Bailey's "numb-numb" procedure
http://www.youtube.com/watch?v=70QHdPe_QS8&feature=related

"I'm gonna scrub my hands and do the scrub-my-hands dance!"

"I wrote my name on it!" (c) Turk
http://www.youtube.com/watch?v=lSRBBujuwgw

"It's SO HOT!" (c) Turk (ok, honestly the last three are all about Faison's delivery. All are both childish and serious)
http://www.youtube.com/watch?v=dMQhpkJqMiI&feature=related

JD tells Janitor a riddle
http://www.youtube.com/watch?v=ezF_JO8agR0

"Hooch is crazy!" This is one of the best recurring season-long jokes on the show, and one of the best parts about the fourth season. Phil Lewis kills this.
http://www.youtube.com/watch?v=4mmRYwGrazc&feature=related

Hi-Fives from The Todd
http://www.youtube.com/watch?v=k_AzCm8Vass

Janitor explains to Elliot why he tricked her into a date. It's not really that funny (cept for Cox of course), but it's really about Neil Flynn's moment to be serious. Nice scene.
http://www.youtube.com/watch?v=mTQWU4A7RuI&feature=related

The Rerun Dance
http://www.youtube.com/watch?v=vI38hJ1m-5Y

"Lady, people aren't chocolates. Do you know what they are mostly? Bastards. Bastard-coated Bastards with Bastard Filling." (c) Cox. One of my favorite quotes on the show.
http://www.youtube.com/watch?v=FTbgvYPVdXE


I'm not gonna post any of the serious moments, because I feel like it would be cheating. I might post the episodes where you can check them out to see the whole thing.