Posting rude/'harsh' memes online makes me happy.
Watching pundits and hardliners defend their positions without a singular hope of convincing other people that they are "right" about everything political cracks me up.
Watching leftists gripe about Ayn Rand and Randianism tops everything else.
Watching stupid, whiny, hyper, spoiled and/or generally bothersome children erupt into tears and wailing cracks me up... until their idiot parents come to calm and coddle them back into reassurance and tranquility. That kinda ruins it for me.