The most confusing and funny glitch I had so far was the well known "character control" glitch where a person glitches into another person's character.
So, I was crashing on my GLaDOS character and tried to get to my home location in hopes of stopping it. At one point when trying this the game then decided to glitch, so I ended up being inside a warrior cat near to a friend of mine. It soon fixed itself, but I will probably never forget it seeing it seems to be a bit of an uncommon glitch.