While at play for this extraordinary stake, they have a fire by them, on which a small pot of walnut oil, or oil of sesamum, is kept boiling; and when one has won a game, he chops off the end of the loser's finger, who immediately dips the stump into the boiling oil, to stem the blood; and some will persist so obstinately, as to have all their fingers thus mutilated.
Source: wiktionary