I think people are mentioning green pubes as a joke, but as I think about it now pubic hair does not seems like such a ludicrous source for 1/6 Joker hair - when you forget the origin, it's probably not that bad a choice to the minds of some. I honestly would not be surprised if it turned out someone had used pubes for a custom Joker and claimed it came from elsewhere. With a lot of customising going on out there, from professionals to complete amateurs, I would have to think one of them at least tried making a pubic hair wig.
I don't mean this as a joke, I really wonder, has there ever been a custom posted where people have been honestly suspicious that pubes were used?