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 from the movie Airplane (1980) where the pilot is sweating so badly that liters of water are literally pouring off of his face. Great one to use whenever something suspenseful is happening.