Rage clicks are the equivalent of spamming a close elevator button when you just want to get up to your apartment. But, instead of a close elevator button, it's a space on your application. And instead of getting to your apartment, users usually rage click when a button isn't working as fast as it should or at all.
A Rage Click is defined as a 2 seconds or longer period in which a user clicks 5 or more times in the same area. This can help highlight points of frustration your users have with the app.