Typically invoked by governmental officials during sworn testimony to the U.S. Congress to deny potentially damaging -- politically and/or criminally -- behavior.
From the 1994 film "Clear and Present Danger" starring Harrison Ford:
Jack Ryan: Who authorized this?
Robert Ritter: I'm sure they'll ask you that.
Jack Ryan: Who authorized it?
Robert Ritter: I have no recollection, Senator
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.