In battlefield, it is the phrase used when a player stabs an opponent with a knife, and steals his dogtags, rendering the soldier dead and tagless. It is the utmost humiliation that one can render upon another player. The phrase should only be used when one of the many painful knife animations are played, and the dogtags of the opponent are taken. It should not be used on knife slice kills. Oftentimes, after this phrase is used, a teabagging proceeds it.
Legend has it that the phrase was coined by BilboTBagginU on the popular "violent industries" servers.