An example of a Freudian slip would be a person meaning to say, "I would like a six-pack," but instead blurts out, "I would like a sex pack." Another example would be addressing one's spouse by an ex-lover's name.
Also known as parapraxis, the Freudian slip was named for Austrian psychoanalyst Sigmund Freud. Freud did not coin the term, but the concept relates to his assertions that people may sometimes "slip" and say something that was previously in the unconscious mind. It does not so much refer to a repressed thought as much as thoughts that one does not wish to express, especially verbally.