This phrase was first started sometime in the 1940's. It's origins are from the National Football League. It's exact origins are unknown but the term was used by players and coaches to describe what goes on during a pile up of players attempting to recover a fumble or a loose ball on the field. Players at the bottom of the pile would often resort to dirty, classless tactics in an attempt to recover the ball from another player while the referees were attempting to clear the pile to discover who had recovered the ball. Often times, players would resort to punching, kicking, scratching, grabbing an opposing players ball sac and squeezing, etc.... in the hopes that the player with the ball would give up the ball to try and stop the other player from "giving him the business". The phrase became known to the general public in 1986, during an NFL game between the Buffalo Bills and the New York Jets when referee Ben Dreith called a personal foul penalty on the Jets' Marty Lyons after he tackled Bills quarterback Jim Kelly to the ground and started to repeatedly punch him in the head. Dreith announced to the crowd: "We have a personal foul on number 99 of the defense — after he tackled the quarterback, he's giving him the business down there, that's a 15-yard penalty."
Player 1: "Who recovered the fumble? Did they make a call yet?"
Player 2: "Dunno. There still in the pile giving the business."