You sign your own ten-pound note. It vanishes from the magician's hands. Five minutes later a spectator cuts open a fresh lemon, and there's your banknote, with your signature and all. How?
Watch this trick in action
The technique: switch, load and the prepared lemon
After signing, the real note is 'switched' with a foldable duplicate (often via a 'thumb tip', a fake fingertip into which the original disappears). The duplicate is supposedly burned or eaten, but the original sits safely in the magician's palm.
Then the magician 'loads' the note into the lemon through a pre-cut slit on the underside, sealed invisibly with a little juice. Some versions use an unbroken lemon into which the bill was earlier pushed through a tiny pinprick using a hollow pen.
A third variant: multiple lemons laid out, and the magician 'reads' which note was chosen to pick the right pre-loaded fruit.
- ✦Thumb tip: false fingertip for bill switch
- ✦Pre-load: lemon is prepared hours in advance
- ✦Invisible slit: seals shut with lemon juice
The psychology: signature = absolute proof
By letting you sign yourself, the magician eliminates every 'it was a duplicate' explanation. This principle is called 'unimpeachable proof', proof the brain cannot dismiss. When you cut the lemon yourself and see your own signature, logic is shut out.
Time-distance also works. The bill vanishes, something else happens, conversation flows, and only minutes later does the lemon appear. This distance makes the brain forget the exact moments where a switch could have happened. It stops puzzling, it accepts.
Bill in Lemon is a 'parlour' trick with the impact of a miracle. A lemon, a banknote, and a signature, that's all it takes.