Nostalgia is the reason for obsession over Thomas the tank engine (in fact, that's the reason why anybody over the age of 15 obsesses over shows aimed at children)
Pooh's Adventures. A meme that sounds quite regular for a strange mind at first, but when you find out that they have plans for a family-friendly "Pooh's Adventures of Avatar", then everything is ruined.
Join me as I take on the worst and most bizarre of these fan-created crossovers, watching as much as I can and browsing the wiki to see what other ideas they have up their sleeves (and won't bother to complete).