When someone punches you in the asshole. Not fisting, being buttercupped is not meant to be sexual in anyway. Only the pains of Satan are intended when someone buttercups another.
Jason: Dude why the fuck did you just buttercup me?!?
Michael: I buttercuped you because you stole my wallet you fuck!
While our lifespan is the number of years we will live, our healthspan is the number of healthy years we will have and our sexspan is is the number of years we will continue to be healthy enough to continue having an active sex life.
A lighthearted reaction upon receiving disappointing news of some sort. Usually something that isn't a particularly a big deal, esp. when it primarily affects someone else - sort of a mild schadenfreude. Sometimes doubled or tripled, and possibly said in a sing-songy voice for added comedic effect to imitate a muted trumpet, which is how the meme originated.