To make a sacrifice on behalf of the group. The “classic” use of the phrase is when a baseball batter deliberately allows himself to be hit by a pitched ball that forces a home run to win a tied game. Another scenario: your pal wants to go out on a date with a real babe, but the babe won't go unless your pal finds a date for her homely friend. Your pal begs you. You accept. You're taking one for the team.