You start with a tray and 3 glasses with a silk on one end and you tell the spectators that you will make the silk jumo to the end glass. You pass the tray behind your back and flip the tray in the process to show that the silk "jumped" to the other end. You do this a couple of times until your audience catches on.

After all the bits of business you hold the tray in plain view the hanky jumps to the middle glass right before their eyes!