The Time Traveling watch trick is performed by David Blaine on a TV special. It is pure street magic at its best.
A Spectator is asked to remove his watch and a magician borrows it...The magician does not carry anything! They then show the wrist watch to some spectators nearby who mentally note the time showing on the watch.
The magician places the wristwatch face down in the volunteer's hand. The volunteer then makes a fist with the hand holding the watch, so it is hidden from view..
The magician does not touch the watch again. The magician then asks the volunteer to think of and call out a number and then to concentrate on that number and the watch.
He opens his hand, turns over the watch, and sees that the hands of the watch have moved that many minutes!!
The props that are needed to perform this trick: the volunteer needs to be wearing an analogue watch. One with an long stem that is easy to manipulate quickly. SEIKO watches are the best for this.
Preparation for the trick: You need to set your own watch to the wrong time.
Method: Ask your volunteer for their watch "I think my time is wrong, may I see yours for a second, please?" is a great excuse to start the illusion. Ask them to remove it.
Now hold the watch for a minute and examine it, look at it, state what time it says, and ask, "Is this the correct time, please, I need to know."
Quickly glance at the time on your own watch, and draw the volunteer's attention to it by setting its time.
While they are looking at you setting the time on your watch, at the same time your other hand is moving the stem on their watch so that the time on their watch is moved forward 25 minutes.
Now have the volunteer place their watch between their hands and ask them to pick a number from 10 through to 30. Most people will pick 25.
If they pick 20, they will not notice it is off by five minutes when you reveal that the hands of their watch have moved forward in time....
If they pick something below that number, tell them to make it harder for you, and pick a higher number.
It gets them every single time... Try to remember to come up with some great patter when performing this trick - it will help the trick move along with the misdirection.