Lee or "barneyfag" as many know him is an omniscient entity that lurks each board(sans porn boards). With his army of bots, he scrapes the images posted to the boards and compares them with images from sites that pony art would be such as DeviantArt, Tumblr, Derpibooru and so on. Should he find a pony image, his bot heads over to the thread it was posted and spams posts to the offender that is usually a variation of "I want you dead". It's nothing eloquent. From what I have seen, the bot merely continues to post the same repetitive phrases should the pony poster continue posting pony or if another poster attempts to directly address Lee until the thread is pruned.
This antic of his has been going on for some 10 years iirc.