In paintball, it is considered unsportmanlike to shoot a player from closer than 25 feet.  Sometimes you can sneak up on a player or if you get too close to him to shoot, you can use the 'Barrel Tap'.  A Barrel Tap is when a player eliminates his opponent from the game by taping him on the back with the barrel of his paintball marker.  The benefit of the barrel tap is you can eliminate your opponent without having to fire on him from close range.  Being as most players at local fields and leagues may know each other and don't want the humiliation of having to surrender in front of his aquaintances, the barrel tap saves him from having to make the choice of either surrendering or being shot at close range.  A common occurance for the barrel tap is when one player bunkers an opposing player.  For the most part, when a player bunkers another player, one of them will end up getting tagged.  Once the charging player gets to his opponent and neither one has been tagged, the player in the bunker will surrender or the bunkering player will execute the barrel tap.