Brain Fart

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.

When you are attempting to remember something very obvious, someting that you know you should know. This feeling often leads to head banging and hair pulling.

A sudden and involuntary (although depending on the source, not altogether unexpected) release of ignorance.

Blurb in your head outta nowhere, train of thought goes weird

When something you were going to say but the thought escaped your memory and doesn't return.

When you do something incredibly stupid by mistake. An obvious mistake that should for a task that's usually very simple.

An involuntary release of stupidity. Usually at the least opportune time.