a benefriend is simply a friend with benefits, giving all the sexual benefits of being in a relationship with said person without having the commitment of a relationship.
Guy: We've been hooking up for a while now, so will you go out with me?
Slutty girl: No I'm a slut and like hooking up with multiple guys. Let's just stay benefriends.
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.