The barracks is a building where unmarried military personnel live, it is mosty inhabited by men. A barracks bunny is a female military personnel who lives in the barracks and has random casual sex with many men in the barracks.
CPL Jones: " man, i havent gotten a piece in a good minute...ima hit up "so and so" the barrack bunny, shes a sure thing"
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.