Quite a few years back, I was banned from a Danish Pokemon forum (I just realized that my forum experiences have nearly been exclusive to Pokemon >_<). While I don't remember the exact details, I do remember getting warnings for spam, which I had no idea what was, as well as someone commenting on my ban about double-posting within some thread I ran. I'd use the excuse that I was only like 10 and that it was the first ever forum I'd gone to, but we've got extremely mature members on here that are of the same conditions, so I don't really feel like that's a valid excuse. In any case, that's the only time I've ever been banned from anywhere that I can recall :p