1 This can mean someone who is ready and fully equipped for the occasion or, to the contrast, 2 it can mean someone is totally out of their mental capacity.
3 When talking about a car or something similar it is to indicate that it is completely upgraded or modified or just generally badass.
4 It can also be a person who is so over prepared it is to the point that it is humorous.
1 Hank is fully duded out for the zombie apocalypse, if something happens we call him.
2 That guy came around the corner fully duded out, I don't think he knows where he is.
3 That fucking car was fully duded out! Did you see the paint job on that thing?
4 why did you show up here all fully duded out? I just need you to hold the flashlight.
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.