Comes from the infamous scene on Good Times where Florida throws the punch bowl to the floor, says "damn, damn, damn!" and starts crying when grieving over James' death.
Today it can be used as a comical interjection, and Black folks are the most likely to get the reference.
Man: You caught my eye and I had to stop...may I call you sometime?
Woman: Thanks for asking, but I got a boyfriend.
Man: Damn damn DAMN!
<woman giggles>
I walked in the room and was like "damn damn damn!" from the pungent must that curled my nose.
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.