5. Pretzels in bed
As long as no one's watching, that queen-size mattress might as well be an enormous dinner table (guys are especially partial to this habit — it has something to do with getting yelled at by mom). Keep it to the kitchen, thank you, and while we're on the subject, try to clean your sheets once every few months, too.
I will admit I'm horrible about this. The other day I cooked dinner for my girlfriend, she seemed in shock when after preparing the meal and fixing our plates I put them on the bed and sat down. I don't own a table, so I just eat all meals on my bed in front of my tv. The living room/kitchen area almost serves no purpose, it's just there for show.