The opening credits scene depicts Kenickie working on a car, only for him to fall under its hood after going in too deep. The car chews him up and finishes the process by burping.
Before the "Summer Nights" number, Doody spots Putzie looking up the skirts of two girls at the bleachers, so he says "HEY!", alerting the girls to Putzie's presence. When they see him, he cheerfully goes, "Hi girls!" before they walk off. Doody then calls Putzie out and squirts him in the face with his water pistol.
Principal McGee's grimace when saying "what bright, clean, wholesome students we have here'' shows exactly what the student body gets up to.
Even funnier when you realize Jan did this after Marty compared her to Bucky in the commercial ("Hey look, it's Jan!") and Jan just goes with it.
Bonus when Marty clobbers Jan with a stuffed animal when she tires of the routine.
Marty doing breast calisthenics at the sleepover.
Danny's hilarious attempts to join a sports team, failing miserably at basketball, baseball, and wrestling, often resorting to fisticuffs when all else fails:
(Danny gets pinned)
Calhoun: You give?
Danny: Yeah, give.
Calhoun: Good.
(Opponent releases Danny, who hits him in the gut and runs)
Calhoun: ...He's a hitter.
The basketball player Danny punches in the stomach? Played by Michael Biehn!
When Danny and the T-Birds begin singing "Greased Lightning", the other shop class students look on with confusion.
Frenchy's retching sound after Sandy gets sick at the sleepover.
Frenchy asking Doody how she looks at the dance.
Doody: Like a beautiful...blonde...pineapple!
The entire Hand Jive sequence, because of how utterly chaotic it is.
When Sandy makes her appearance at the end, post-makeover, the T-Birds have a sudden case of bug eyes and dropping jaws,...and The Pink Ladies are laughing at them.
Followed by Principal McGee's assertion that "just because the pictures aren't of your faces doesn't mean we can't identify you", espousing the belief that the FBI is capable of finding out who the boys responsible for mooning a live television broadcast were by identifying their buttocks in the kinescope footage, and is moreover actually interested in doing so.
What's more, judging from the increasingly worried expressions on the T-Birds' faces during the announcement, it's heavily implied that they do in fact give themselves up out of fear from the announcement.
The 2016 televised musical
This exchange between French and Doody at the drive-in.
Frenchy: I wish there was a way I could watch movies at home, any time I wanted. Doody: Let's just get to the Moon first.
The reaction to Sandy's makeover before "You're The One That I Want" is just as funny as before, but this time, Danny nearly PASSES OUT when he sees her.
During the show, Anna Kendrick tweeted that she figured that Eugene would be better in bed than any of the greasers, and that she would "hit that" upon his first appearance in the special. Cue Eugene's actor, Noah Robbins, finding these tweets, quoting them, and responding, "Please DM me", the second in all caps.
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