Not sure if there is merit to a viable lawsuit, but suspending/banning the kid is a viable alternative. Maybe list a code of conduct.
If someone can explain to me the "hilarity" of giving the finger to a camera? Why is it funny and why do onlookers laugh like they heard the funniest joke of their life?????? Its classless, low life, ghetto and future employers could find the picture and say, "Do I want this person representing me and my company?"