Their little white worms that come out your asshole at night and lay eggs.WHen you scratch your ass your fingers pick up the worms then you put it in your mouth.This is really common! if you want to catch these worms put tape over your asshole and they can lift out.They are half an inch and you'll have to catch them at night. They're little parasites and a sympton of them are a itchy asshole.
The left side is a more severe case of worms that live inside humans
The ride side is the common pin worm.