When I was a little kid, my dad used to take me to Pawtucket Red Sox games. Part of the allure there was getting to see the future stars of the Boston Red Sox before they made it big, and occasionally getting an autograph. Kids (including young me) used to cut the tops off plastic gallon milk jugs in order to hold a baseball, tie a string around the handle and lower them outside the dugout, where the players would take them out and sign them (I ended up with autographs from Mo Vaughn and Eric Wedge this way). Above, you can see a number of fans fishing for baseballs at Citi Field over the weekend. I can't quite tell what they are using, but it appears that at least one was successful at shagging a batting pratice ball.
Seems a bit more effective than booing unsuspecting camera people who poorly (BUT LEFTHANDEDLY) throw batting practice balls back to opposing players. Happened while I shot Bark at the Park.