This word is basically the word "what". Except for the fact that it has four "a"'s and no "t".
Whaaaa is a word to showconfusion, shock, or just to show that you have no idea to what just happened. The word "Whaaaa" usually has a question mark behind it.
Paul: "I can't believe that just happened! Did you see that?!
Doug: "Whaaaa?"
Waaagh! is the psychic field that Orks in Warhammer 40k produce. The psychic energy produced in the Waaagh! is the main reason that Ork technology even functions, as without it, most of their weapons and vehicles would be unable to work. The Orks also use it as a battlecry.
The word is always spelled with at least three As, though more are used when expressing an especially long or excited battlecry.
'Ey Boyz, we gotz da Waaagh! on our side, we ain't losin' ta no humies.
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.