Contestant slaps man into unconsciousness

It's not every day one can win a bout with a 'TSO' – total slap out – but that's exactly what happened when two rivals met in a make-shift slap contest in the US.

The bizarre footage was captured when the two grown men decided to join a group of adults slapping each other for supremacy at the Ink Masters Tattoo Convention in Texas.

The contestants line up on opposite sides of a table and take turns in giving each other an open hand crack across the cheeks.

However, the battle quickly comes to an end when, surprisingly, one rival feels the full force of good old fashioned slap and falls to the floor in a heap.

It's not known whether the blow left any lasting damage, but concern for the fallen slapper was apparent with a number of people gathering around the stunned man.

Meanwhile, the victorious champion soaks in the adulation of slapping a man into unconsciousness.