The road agent's spin, also known as the "Curly Bill spin" (after Curly Bill Brocius), or the "Border roll" was a gunfighting maneuver first identified in the days of the Old West. It was utilized as a ruse

Deception

Deception, beguilement, deceit, bluff, mystification, bad faith, and subterfuge are acts to propagate beliefs that are not true, or not the whole truth . Deception can involve dissimulation, propaganda, and sleight of hand. It can employ distraction, camouflage or concealment...

 when forced to surrender a side arm

Side arm

A side arm is a weapon, usually a pistol but can be a dagger, as used in pre-modern times, which is worn on the body in a holster to permit immediate access and use. A side arm is typically required equipment for military personnel and sometimes carried by law enforcement personnel...

 to an unfriendly party.

Normal Old West procedure for surrender of a loaded pistol called for it to be handed over upside down and butt-first. A well-trained gunfighter could hold the pistol upside-down by the trigger guard using the index finger and extend it toward the surrenderee as a false sign of compliance. When the surrenderee reached for the pistol with their (presumably dominant) hand, a sharp, practiced motion of the wrist would quickly flip the gun forward and back into firing position, catching the surrenderee off guard and unable to react.