A Freudian slip.
Q: what does Oedipus the king's mother wear under her dress? A: a Freudian slip
Two. One to hold the ladder and one to screw your mother - I mean light bulb!
A Freudian slip is when someone says one thing when thinking of amother.
A monster makes bigger holes in the skirting board.
Because sheep can hear a zipper from a mile away.