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 gif of some guy mashing the F5 key on his keyboard. In case you're a computer novice, the F5 key refreshes the page that you're viewing. This can be used as a reaction for whenever you're watching an argument unfold etc.