When you get really confused about something and mess it up.
Ex- getting confused when your shift starts and show up at a completely different time.
Or-
Mixing up the dates of your doctor's appointment and show up on the wrong day.
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.