4 color shoelaces are displayed, all held together, side-by-side, in one closed fist with the ends of the laces completely visible.
The performer then explains the premise; a "Russian roulette" type effect... 3 of the 4 shoestrings will be grabbed - and PULLED - from the performer's hand, one at a time, until only one string remains in the hand.
He says that he's "pretty sure" he knows which string will be left behind, and so has made a prediction... He has tied ONE item to ONE of the strings... This item is hidden in his closed fist.
After a couple of FREELY SELECTED shoelaces have been stripped from the performer's hand, the performer tells the audience what the hidden "mystery" item is; a RAZOR BLADE.
"So you understand," explains the performer, "that all of these strings will slide freely from my tightly closed fist...except for one."
Tension builds as, one by one, strings are randomly pulled out by different spectators. They with only two remaining the spectator is asked to grab one. Suddenly the performer wildly pulls his fist back, freeing the empty string. Now only one string remains in his hand.
With no funny moves, he opens his fist, revealing A VERY REAL RAZOR BLADE.