Refers to a human being who possess a face with comedic qualities, such that the face can be considered to be a joke. This results in people viewing the face to laugh or smile at the comedy.
When someone is so attracted to the concept of the Joker from the Dark Knight film that they get physically turned on, this leads to them wanting there sexual partners to become more like Heath Ledgers Joker, making them wear make-up or even giving them there own Chelsea Smile, after this they are mounted and ridden for hours on end until the person who actually did the Jokerfacing is worn out.
Man 1, Oh god, He has been Jokerfaced!
Man 2, Oh No....but I bet he enjoyed the sex
Woman 1, Oh my god I just Jokerfaced that guy!
Woman 2, You are sick!...But how was it anyway?