2. Never pee on my bed
I had a college roommate who had been a high school best friend. He was sometimes a jerk, particularly when he was partying. One night we had both been drinking. I’m not exactly sure what was said, but he left the room, and apparently went and peed on my bed. He then left the room and went to a mutual friend’s dorm. I went and watched my sheets and flipped my mattress over, then poured a bunch of water all over his bed and put a nice looking lump of peanut butter on his pillow (I couldn’t bring myself to actually pee on his stuff). Then, I went to our friend’s place where folks were hanging out.
He had this sly look on his face when I came in and he made a comment about peeing on my bed. I told him that he was a moron for doing that and then leaving the dorm with his room unlocked. The look on his face flipped in a second and he ran out of there. I had locked my door, so I had a good laugh about it and brushed it off.
When I went back to my room later, I discovered that he had gotten into my room. (I later found out he had gone to an RA, told them he lived in my room and was locked out, and they unlocked my door for him and left him alone. WTF.) He peed on my bed (again), peed on my cell phone, peed on my computer, and peed in a bottle of pills (that I had a prescription for). Hundreds of dollars of damage.
But that wasn’t the worst part. The worst part was that, while I was dealing with the fallout, he was hanging out with our mutual friends and a group of girls we were all friendly with. I don’t know what he told them, but none of them would even speak to me afterward. They wouldn’t even tell me why they weren’t speaking to me. He decided that he was just going to ignore me and our mutual friend/roomate and pretend we didn’t exist for the rest of the year. He poisoned my relationship with high school friends, and new college friends, and after an evening in which he did the most vile stuff I have ever experienced. And I couldn’t even bring myself to pee on his bed.
He has reached out to me over the 15 or so years since then. In big groups I can be polite, but this is the only person I have ever not been able to forgive. To rub salt in the wound, he is still friends with a girl I was crushing on at the time, and who I know had been attracted to me as well. She was a part of the group that never spoke to me again, and it has to be because of a lie he told her.
Also, he continued to leverage the relationship he had developed with a relative of mine who was kind of a big deal at the university and in the town. My relative would tell us to get together and work things out, and I would say I can’t do that and ask him to cut off contact. He thought we were just in a spat or something, and kept trying to be a mediator. While continuing to help my “friend” and get him into programs at the school, and jobs afterward.