On a display stand are 4 inflated balloons marked 1-2-3-4.
Spectators select any of the numbers, and the balloon at that position flies up and away from the stand.
This is repeated for the other 3 balloons.
We supply the special stand responsible for the effect. You can use any balloons.
The effect of the balloons flying off makes for a good comedy situation in addition to the mystery aspect of the effect.