A week ago Squidbrain posted a question on the popular social news network Reddit, Can you get .gifs with sound? The answer to Squidbrain's question is no, because a gif is an image file standard that supports animation and not (currently) sound.
However there has been a thing running for a little while called YoutubeDoubbler where you play two YouTube videos together that overlap in a nice way.
The same thing exists for gifs and the website for that is GIFsound.com.
Cooking Meat
Dancing Dog
Daft Punk
Nyan cat
Hypnotoad