Sharing may be caring, but using without permission is cause for petty revenge… Sure, roommates share things all the time but those items are usually agreed upon by both parties. It's not even about being possessive of one's belongings; it's financial as well. If you and your roommate share groceries, then the cost for groceries should be split evenly amongst everyone in the household. Some of you are probably wondering why this needs to be addressed, but you'd be surprised how many entitled ro…