Concept: An individual is able to maintain a sexual intercourse by occasionally performing sleights and effects. If he is to perform on and on without failing while he's doing his deed, the intercourse never ends until she tells him to stop.
Ideas
You can introduce the two characters in a mockumentray / voice-over fashion.
You can tell the spectator that the man can keep on having sex as long as he performs magic and the woman can have plenty of orgasms as long as she tries to heckle him.
You can present more than one couple. Another couple can be presented with the man having to DJ and the woman finger tutting in order to maintain having intercourse.
Philosophy
In a way, the sex act is a metaphor for what happens when someone does something artistic and someone else compliments their act by reacting in a certain way (dancing, singing, etc.)
I would rather not evolve more on this concept, but rather leave each one of you to think of how he/she would transform this into a small story/sketch/patter.