Thinking about how, on multiple occasions, I told my past "friend" to be cautious about certain other people, and each time they ignored me and became friends with them anyway.
Just for them to tell me later on that those people actually suck for one reason or another. Like, yes, I wasn't "capping" when I told you why I didn't like them, but you never listen to me so~
Not my problem anymore, just something I think about that makes me laugh sometimes. ^^