My ex-boss got banned from a local Chinese all-ya-can-eatery when he got caught stuffing a bunch of egg-rolls in his pockets to take home to the wife and kids.
No, really.
One kid would buy, eat for a while, his friend would come in, take the plate up for more, the first kid leaves, second kid pigs out, third kid shows up...They weren't even very sneaky about it because they knew the Japanese staff would be reluctant to confront noisy aggressive American kids.
There was a lot of whining about it, but they changed the rule to no teenagers unless accompanied by an adult, and that solved most of the problem.