How to exact revenge upon one's roommates.... subtly

I knew this was going to be a tough year when I had to explain what an "attention whore" and a "cupcake" are in the same day.

I have had a few minor issues with some of my roommates. Generally ones that involve them treating me like I'm 20 years old. Let me tell you, I am fairly mature for my age. I don't act like a tween anyways, so I resent being treated like one. Thus, I have perfected a few techniques to subtly, yet extremely satisfyingly, exact revenge upon one's roommates.

1) Use their (preferably fairly fancy, expensive) shampoo/conditioner/hair products whenever they're not around. This leads to nice hair on your part, and excellently confused faces and frustration on theirs.

2) Hide their keys. Lock the door when you leave the apartment. Their anger is frankly delicious.

3) Eat their food. I'm not talking obviously, but like, if one has a bag of pretzels, or candy, and they hae already opened it, take a few out every couple of hours or so. Unnoticeable to them, but they will wonder why in the heck they have to buy more pringles all of a sudden, when it definitely didn't feel like they ate that much. Heh heh heh.

4) Milk. Drink their milk. You may wonder, don't people notice when they're missing half a gallon of skim? Here's the best part of that: You fill it up back to the level it was with water. Not only do you get free milk, but they get nasty, odd tasting watered down milk that makes them wonder what was wrong with the cow. Mwahaha.

I will likely add more as I remember/think them up. Look forward to more tips and tricks from Eppy on how to exact revenge on other, coming soon. >:)