The weirdest thing that happened to me was about one year and a half ago at the start of 12th grade.
One guy from my class that liked to do the most random things would troll my best friend saying she was looking at his butt (most times she wasn't even looking at him). One day, out of nowhere. he turn to her and said he was bissexual (he really is) and she kinda laughed (I believe she wasn't being mean, but it may have been because I had already told her in the past that he was bissexual). He thought she was making fun of him and he stopped talking to her. Some weeks later, I was talking to her on Facebook and commented she should try to talk to him. She was unsure, so I told her (in a joking tone) that I was going to create a group conversation between them so they could fix things up. She told me not to because it didn't matter anyways. I understood, but to scare her I created a group conversation between us and some other friends and named it "Stop looking at my butt!" (the phrase he always told her, but in portuguese of course). She panicked at first, but, after realising he wasn't really in the conversation and when I thought she had calmed down, she started insulting me (through chat), saying I was revealing her secrets to random people (as if that phrase was some kind of shocking secret, even after all the times he yelled it at the world) and stopped talking to me.
It was horrible. Initially I felt bad with myself, but after some time I realised I haven't done anything wrong, specially after she started to part with every single one of our group's friends for the most stupid reasons, so I eventually moved on and nowadays I'm grateful that she made me the favour of walking out of my life.