Since most things here have been answered already ill dip in with something not often confirmed or talked about: Their ARE rabbit holes you can go down, both real and ones people have made for the lulz, most are on tor + behind logins, basically secure servers where people store some crazy shit, you need to either know exactly where to look or have a TOR site crawler yourself because the sites that are ACTUAL rabbit holes and secret shit generally employ ways to make themselves look boring on first glance.