Wild Bill Hickok

James Butler Hickok (May 27, 1837 – August 2, 1876), better known as Wild Bill Hickok, was a famous Earth lawman. He was shot in the back while playing cards, and was the origin of the "Dead Man's Hand" involving aces and eights.

Tobin Dax learned all of this from the book, 99 Great Card Tricks You Can Learn in Your Spare Time. (DS9 short story: "Dead Man's Hand")