In linear algebra, an n-by-n square matrix A is called invertible (also nonsingular or nondegenerate) if there exists an n-by-n square matrix B such that:
AB = BA = I (where I is the Identity Matrix).
Otherwise, in life, it refers to the case where something can be transformed into something else and transformed back.
Randy: Sally is so invertible; real marriage material.
Sandy: I know, nonsingularly so. Put a few drinks in her and you can get her on her back and yet in the morning she still gets up and cooks you breakfast.
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.