A lacrosse passing drill.
There are three lines of players (A, B and C) at the fifty yard-line facing the goal. The middle line (line B) is supplied with all of the lacrosse balls. The first players in each line start down the field, the middle line cradling the ball. Player B passes the ball to his left to player C, and runs behind him to take his place at the left wing position. When player C receives the ball, he crosses the field to pass to player A, then runs behind him to take the right wing position. When player A receives the ball, he crosses the field and passes to player B, then runs behind him to take his position, and player B crosses again to pass to player C.
Get it? It's hard to explain, but in broad terms, it's a lacrosse drill in which the attack wings making long, leading passes across the field while advancing toward the goal. The extra person just makes each line replenish itself.
Add 1, 2 or 3 defensemen
Finish with a shot on goal