A garboon is a more specific racist term than words such as "nigger" or "coon". It refers to large black men (or women?) with particularly stereotypically "black" features, the likes of which would be found in a racist portrayal, e.g. enormous lips, wide and flat nose, extreme prognathism. Possible etymologies include the word "baboon" and "Gabon" (an African country) and the fact that the word sounds like some species of ape.
Did you see that garboon with the horizontal vagina of a mouth on his face?
To sniff a recently used seat. This practice specifically refers to bicycle seat sniffing, though can refer to any seat. It is also usual practice to gaboon a seat that has been sat on by another, preferably unknown to yourself, person.
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.