Annoying roommate!!

So my SO and I have this roomie who is just downright weird! He talks about ridiculous stuff as if we think it's hilarious but he's laughing his butt off and we aren't... he also is an impulsive buyer and will buy stupid things like more Tupperware containers then we really need and junk! He doesn't even clean up after himself, he leaves dishes everywhere, passes gas all the time in front of us. He doesn't even care and we are the ones picking up and cleaning afterwards. He's annoying! How would you handle this???