When you see or hear something g funny (not too funny) and it causes you to push air out of your nose at an abnormally fast rate in place of a laugh... a snicker with your sniffer, if you will.
That dank meme on ifunny made me sniffcker, but it wasn't funny enough to make me actually laugh.
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.