Installing the track for the drawer of your IKEA desk backwards so that the drawer opens in toward the wall and not out toward you.
Picking up a prostitute that you thought was a woman but turned out to be a tranny.
Picking up a prostitute that you thought was a tranny but turned out to be a regular old boring chick.
Removing a patient's right leg during surgery when it was actually the left leg that needed amputating.
Joining the Church of Scientology.
Giving Dr. Phil a TV show.
These are MISTAKES.