But there is one thing which the severest and the mildest cases all have in common, and which is equally found in parapraxes and chance actions: the phenomena can be traced back to incompletely suppressed psychical material, which, although pushed away by consciousness, has nevertheless not been robbed of all capacity for expressing itself.
Sigmund Freud, 1904
For Freud, daily life was filled with examples of how wishes and ideas that we would rather not face find some form of expression. They escape our conscious control and emerge in our jokes, habits, and seemingly "accidental" gestures.
Parapraxes are slips of the tongue, now, of course, commonly called "Freudian slips."