Gif Central boasts hundreds of funny animated gifs. Only the best of the best make it onto this site, with most of them having an accompanying source. No tumblr-esque one-second-long disappointments. No obscure titles or descriptions.
This is an animated reaction gif of Michael Scott quietly saying "I'll kill you" while he conceals his face with his hands. This is typically used whenever somebody wants to tell somebody to knock it off. This is from the TV show The Office (US).