Basically, it's synonymous to "Hit it and Quit it". Smash it and Cash It refers to having sex, (Smash It), and then bragging to all your friends, (Cash It).
It can also be used as: You have sex with a prostitute (Smash It) and then pay her (Cash It).
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.