I can't believe I've not said this already (at the risk of it having already been told) when it's my favourite musician-related-gag.
Stevie Wonder's playing a gig, and after a few songs things are getting a bit more intimate with the audience, so he asks if there's any requests.
'Play a jazz chord!' a guy on the front row shouts. So Stevie plays an Am7.
'Naw, naw, play a jazz chord!' the guy says again. So Stevie plays an Am7b9add11.
'Naw, naw,' the guy says again, 'play a jazz chord...to say I love you.'