Buffy The Vampire Slayer S02E05

Reptile Boy

 Upset again at Angel, Buffy lies to Giles and goes to a frat party with Cordelia, where their dates drug them and chain them in the basement. The house brothers worship a snake demon and sacrifice girls to it annually in exchange for wealth and power. Giles, Angel, and Willow compare notes and meet up with Xander just in time to help Buffy break up the cabal.