Something you'd call someone who is small. Sometimes it is used as a term of endearment but it also can be used as an insult or a way to make fun of a short person. The person being called Chibi Chan is in denial about being short most of the time.
Tall person : Hey, Chibi Chan!
Short person : Stop calling me that, loser!!
Tall person : But I want nothing but to love and support you! You repay me by calling me names?
Short person : Whatever. Go away!
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.