From Wikipedia.com

A Freudian slip, or parapraxis, is an error in speech, memory or physical action that is believed to be caused by the unconscious mind.

Example:

Imagine sitting with your spouse at the breakfast table. You’re both tired, not yet awake and it’s still early. You’re about to ask for butter but managed to say the following instead:

You ruined my life, you bitch.

And that, boys and girls, is a Freudian slip