Idea.

Freudian Slips. Something hilarious, and yet there is a more scientific part to it. When you say something that you didn't want to say, does that mean that you're thinking about what you actually said? I say sometimes yes, but most of the time no.

http://en.wikipedia.org/wiki/Freudian_slip
"A Freudian slip, or parapraxis, is an error in speech, memory, or physical action that is interpreted as occurring due to the interference of some unconscious ("dynamically repressed") wish, conflict, or train of thought."