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.
You didn't get any napkins with your takeout pork fried rice? Womp womp.
Headphones for people who would rather look like a retard than buy a good pair of headphones. Examples are typically found made of injection-molded plastic, worn by only the most 'dank' and 'steezy' motherfuckers out there. Don't be a retard, stick with Grado, Sennheiser, AKG, and the other good brands, and leave this shit for the people who don't know any better.
My friend bought a pair of skullcandy headphones, and they fell apart when I looked at them so I kicked his ass.