An insult. Saying someone has 3 eyes expresses offence at an action and/or phrase that they may have just said. They will probably feel embarrassed and ashamed at this, and too right! They deserve to.
"You've got 3 eyes!" **points at persons head with index, middle and ring finger in a sort of triangle**
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.