thought abortion

When you start to say something and you stop partially through the thought and you completely forget what you were thinking. The thought is terminated before it is finished.

Kendra: I have a great idea for what we should do tonight!
Jenna: Awesome! What is it?
Kendra: We should get in the car and go downtown to go and.....
Jenna: And what?..
Kendra: I can't remember, it just completely left my mind.
Jenna: Oh, you must have had a thought abortion.