I’m interning in Hawaii for the summer, and I rented a room in a house that already had 5 people living in it, all between 19 and 40. I bought a bottle of vodka and kept it in the freezer - vodka is always good to have around in case you want a drink - only to find out one morning that someone drank the entire thing, leaving literally half a shot in it (maybe thinking that I won’t notice that the entire thing is gone). No one confessed, so I bought the cheapest vodka I could find, and filled the old bottle (of Smirnoff, nothing too classy), along with a handful of crushed, strong laxatives. Sure enough, a couple of days later I heard moaning coming from the bathroom, and upon checking, I found out that the bottle is half empty (or half full, at that point). I took a post-it, wrote “Don’t touch my vodka again, asshole”, and put it on the wall across from the bathroom. Revenge!