You're sitting on a train on the way to work.  Then, a complete stranger does this...

Photo Credit: Courtney Wertz MacIntyre

Apparently, this person sees nothing wrong with putting her dirty, bare foot up on the seat of a stranger on a train in Chicago.

This happened to my friend Courtney yesterday.  How she snapped this picture without throwing up in her mouth, I do not know.

What's the strangest thing you've ever witnesses while using public transportation?  Let us know on our FaceBook wall or on our Twitter.