It isn’t that the trick doesn’t work, it’s that it works for real. He pulls the rabbit out of the hat, but it isn’t a plant, there’s no false bottom: he just reaches in, and there it is, where no rabbit was before. And every time he puts his hand inside the hat, there’s another one.
Soon, he’s covered with rabbits, of all colours, sizes, shapes. They start to whisper things that he won’t remember on waking.
When he tries the trick again in actual performance, Karl freezes and has to leave. The show after that, he sticks to cards.

