I love 2 do magic and i think the best magician is CRISS ANGEl. You'll need to have your shoes already tied, be wearing long baggy trousers and have a pair of extra shoelaces.
Before approaching the spectators, do the following:
1. Grab one of the extra shoelaces, and run it through your trouser leg from your waist (just poking out by your belt) to hanging out where your tied shoe laces are.
2. Repeat the same with the other shoelace in the same leg.
3. Arrange the laces so the tied ones are hidden under the trousers, and the un-tied ones are looking like they have come from the shoe.
You're ready to go...
There are two ways to do this.
1. Wait for a spectator to tell you your shoelaces are untied.
OR
2. Act as if you have tripped over you shoelace near a spectator. If you are doing this, make sure the spectator notices it was your shoelaces that made you trip.
Either way, they both lead to the same performance.
1. Smile at the spectator and look down at your 'un-tied' shoe. Naturally the spectator will do the same.
2. You now need to use misdirection. This is extremely important, as if they notice it, (although they may still not know what happened) it will ruin the trick.
The Secret Move
The shoelaces that are hanging out just a bit over the top of your trousers come into play here. When the spectator looks down at your foot, quickly grab both ends of them, and pull them down as you shake your foot. Pull the shoelaces into your pocket, so they do not hang by your side. (Which will destroy the trick.)
Move your trousers a bit over your ankle to show your shoelaces have tied themselves. Then simply walk away.