If someone is really mean to me(and I can't do anything about it without looking petty), I come up with extensive long-term plans to get back at them. I usually don't go through with them. Usually. Eventually I get bored being angry and move on or life knocks that jerk down. Actually, life is what keeps me from being crazier. I'm also pretty nonviolent.
But yeah... Combine my planning with my social media stalking and yeah... It's not the best combo. In college, a chick left an anonymous note on my door, demanding I take shorter showers. Only one chick on the floor always had her damn dorm door open (so she could watch people go by) so I knew who it was. However, I didn't know anything about her other than her vague appearence, first name, dorm room, and the first letter of her last name. We had no mutual friends. Well, I marched my petty ass right down to the computer lab and an hour later, I knew her full name, what her extracurriculars were at our college and in high school, where she had gone to high school and grown up, who her friends and family were...etc.
Now... Had she pissed me off more, my plan would have grown elaborate and I'd have eventually gotten bored and moved on. Instead, this was just a small offense so I wrote thanks for the note, on the back of her note. Mada sure to thank her first and last name specificaly. I slipped it right under her dorm door, during a rare moment of closed-ness. I must've been just getting home from the art building too, when I delivered it so... Midnight ish. The next time I saw her in the hallways(from then on her door was always closed) I informed her of the many other available bathrooms in our hallway/house and left. We didn't talk again after that but I like to think someone learned a valuable lesson that day. I also wasn't doing the sleeping thing much in college so that didn't help my sanity any.