Unless you're at Wrigley Field, you will be removed from the game for doing this.

http://ftw.usatoday.com/2013/10/boston-fan-snatches-home-run-ball-from-womans-hands-throws-it-back/

Game was in Boston - and the Red Sox were getting beaten rather badly. It was getting painful to watch.

When the Tigers got a home run putting it at 5-0... this fan said 'fuck this' and threw the ball back.

But then Ortiz hit a grand slam in the 8th the allowed Boston to come back and win the game. 

Never give up!

It is mildly unsportsmanlike to toss a ball back, but yanking it out of someone else's hands to do it is especially unsportsmanlike.

When Torii Hunter flew into the Red Sox bullpen and hurt himself, it was good to see the opposing team come over to check on him and summon Tigers' trainers. Some good sportsmanship on display tonight, but that ball getting chucked back was not part of it.