Assuming that professional wrestling counts as a sport, why not explore the following approach.
Wearing a traditional professional wrestling outfit, nothing too flashy, the performer has a playing card selected and signed by a member of the audience. The selected card is returned to the deck and the deck freely shuffled by several audience members. A third audience member is given the shuffled deck and told to place it in his mouth, tightly gripping it between his upper and lower teeth. He is instructed to stand over to one side of the performing area.
All is now set for the climax. The performer takes a few paces backwards and then charges forward with an explosive five step run-up, launching himself into an almighty 'flying drop kick' to the side of the audience member's head, knocking him to the ground and scattering the deck of cards (and perhaps a few teeth) all over the ground. All except for one card, the signed selection, which has somehow magically remained gripped between the audience member's teeth.
If your proficiency with the 'flying drop kick' is limited, just replace it with a hefty 'forearm jolt' to the side of the head. This is far less impressive however than the 'flying drop kick' version.
[ February 19, 2002: Message edited by: John Pezzullo ]