In seven seasons, for a show so damned serious, there have been many.
Cordelia’s nightmares in Nightmares - bad hair, Nerds-R-You, the chess club. She’s freaking adorable when they’re dragging her off and she’s got that outfit on. :D Also, the scene they ran over the credits in The Puppet Show. After the scariness of the talking puppet and the missing organs and such, to see Buffy reciting her lines in exasperated monotone, with Willow’s terrified delivery, was totally awesome. Buffy’s the Slayer, from last to ancient first, and there she is, a normal “I can’t believe they’re making me do this” teenager. It was such a great contrast. I loved that little lemonade scene in School Hard where Willow asks Buffy how much sugar she used in the lemonade right as she takes a sip, and Buffy replies “sugar?”. The look on Willow’s face as she tastes Buffy’s concoction is hilarious. Cordelia with the spatula in Homecoming. Any time Buffy drives is comedy gold. Giles and Joyce in Band Candy. When Xander and Oz are cautiously, oh-so cautiously approach a tied-up Buffy in Living Conditions, wondering how tight they got the ropes while Buffy just watches. Cave!Buffy slowly falling off of her chair in Beer Bad. Spike’s “You made a bear! Undo it! Undo it!” in Pangs. Buffy teasing Spike with her neck while he’s changed in the bathtub Something Blue, Giles frozen look when Buffy-in-Faith busts into his apartment and demands he quiz her to test for Buffy, and that she didn’t know what a stevedore was, nearly all of Superstar but most especially the opening credits. Giles and the Drac babes. Spike, The Big Bad Vampire, all nervous and stuttery when Buffy pulls him out from behind the tree. Drunk Buffy and Spike’s face as he watches her, omg. The way she tries to slay after a few shots. Clem and Spike. Dawn on the back of Spike’s bike with a football helmet on. I love that image – Spike the Vampire and the Slayer’s little sister. :D
There’s probably more. But I’m tired. :)