A phrase used often in the canceled TV show "Arrested Development". The phrase is mostly used when the characters talk to themselves after a serious of poor choices/bad events. It's used to make light of bad situations, although the characters themselves don't find it funny.
MARTA: "I was really worried about you"
GOB: "You've got nothing to worry about. We're going to be together for a long time"
MARTA: "We're family now - I'm so happy. I'm going to call the kids!"
<MARTA walks out of room>
GOB: I've made a HUGE mistake
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.