I frequent an IRC room for the popular webcomic xkcd, and this reminded me of years ago, when someone conducted an awful April Fool's Day "prank". There were three different bots in the room and I guess one of the maintainers thought it would be funny to get them to respond to certain phrases of affirmation or agreement with similar things like "indeed" "quite" "very much so", or something along those lines. But then they would also respond to these words if another bot said them, so you got ~30 messages of bots all agreeing with each other once one of them saw something it liked. They eventually failed to keep up with each other, or maybe somebody was cautious enough to somehow make sure it didn't go on infinitely, I never asked. But this happened repeatedly for hours. Not even the worst prank to occur in that channel, though.