When you
mean to do something really obvious but then you forget what you were doing and end up doing something something completely different. i.e, when you have a wrapper in one hand and
food in the other, and throw away the
food and try to eat the wrapper.
Brain Fart:
Person 1:
Man, I had such a brain fart today.
Person 2: What did you do?
Person 1: I was holding
food and a wrapper and threw away the
food and tried to eat the wrapper.