HOLY CRAP! It was SPIKE!!!!
Quote:
From other things a stick does pushups in a dark cave until it throws up
SRSLY! I can prove it!! In the episode Gone, Buffy goes to visit Spike when she's invisible, in his mausoleum, where his bedroom is located underground in a CAVE! They have sex, hence his STICK! Then Xander shows up and (Keep in mind Buffy is INVISIBLE!) sees Spike, naked, on his bed, slowly riding something. So Spike, the uber genius vampire, starts doing push-ups, INTO BUFFY! (It's funny she makes this really weird 'uh!' sound.)
Course the only flaw with your metaphor is that Spike's stick doesn't throw up. When he gets off Buffy to talk to Xander, and Xander leaves, Spike gets upset (THEN STANDS UP COMPLETELY NAKED WITHOUT A SHEET! THE ENTIRE FEMALE POPULATION CURSES BUFFY'S CONVENIENTLY PLACED LEG! whoo..) and then tells Buffy to get out.
SO you see, that metaphor describes Spike PERFECTLY!