Thanks, Tyler. I don't think that's the one, but I'll look at it anyway, because it might help with what I'm trying to do.
I'm playing with Ken de Courcy's Ultimate Faulty Follower, in which the spectator and the magician each have a packet of four cards, and the spectator imitates everything the magician does. Despite the imitation, the magician's cards end up all face down, while the spectator has one face-up card. This happens three times. My plan is to have the card that keeps turning face-up be a joker -- jokers being mischievous. In other words, the spectator didn't do anything wrong; the joker just has a mind of its own. It occurred to me that it would be really cool to have to joker play some other pranks, too.
What I thought of may well be too hard for me: have the joker (in spectator's packet) change places with some card in magician packet. Something like what happens in Jennings' "The visitor." But perhaps people have other ideas for tricks that the joker could pull, tricks that would be easier than the sudden appearance of the joker in the "wrong" packet?