Rochambeaux Dragon
I dreamed that I had an irresistably funny idea for a short movie. It would be a mock trailer for a kung-fu movie where all the combat would be rock-paper-scissors instead of the characters actually hitting each other. I visualized the climactic fight scene in some detail, with the hero acrobatically leaping and twirling about, presenting handsign after handsign to masses of identically-clad opponents, who would then collapse, defeated. When he's disposed of the cannon-fodder opponents, there'd be a protracted battle with the boss badguy, with a whole lot of wirework and grimacing, producing simultaneous identical handsigns again and again before good finally manages to triumph over evil, and rock over scissors.
The second chapter of the dream consisted of a fictional asian friend trying to impress on me the importance of having an asian actor potray the protaganist.

comment by bluepapercup:
This is possibly one of the funniest things ever, largely because of the phrase " dreamed that I had an irresistably funny idea" which just reminds me of the funniest dream I ever had (at Firefly) which then makes me start laughing all over again.
Plus it's a really funny idea for a movie.