10 photo manipulations to mess up your mind with

There's brain teasers which are great for messing with your mind on a mental level and then there are visual manipulations that either have you wondering how the photographer did that or whether you just suffered an acid flashback.

These ten are from a larger collection of some great photo manipulation work by Erik Johansson. I'm betting most will have you doing the ol' scratch the head how'd he do that. a few though are definitely flashback material.