Yeah, this is a huge problem. I was on a business trip once and eating dinner at the bar of TGIFridays. I normally wouldn't eat at a chain restaurant like that, but I was in Virginia and there was nothing nearby.

In any case, these college kids were sitting at the bar next to me, and we started talking. They seemed to be friends with the bartender and one of the told me "give the bartender a $20 and you'll drink all night for free." This was a Friday and I was stuck in VA for the weekend, with my hotel across the street so I was like, OK. Anyway, I slipped the bartender a $20, and he proceeded to make all kinds of drinks for us. He was using the top shelf liquor, not the well drink stuff, and he was making all kinds of custom martinis, shots, etc. We literally finished well over $200 worth of drinks in the space of a few hours. When the check arrived, it only had my meal on there, and all the drinks were missing.

Essentially, the bartenders gave us about $200 worth of drinks and we only paid for our meals, plus $20 each in tips (there were 4 of us).

If I owned that TGIFridays somewhere in VA, I'd be seriously worried about how much money my bartenders were stealing from me. It is literally stealing when a bartender can make an extra $100-200 a night just by slipping free drinks to his friends. I guess the markup is so much on alcohol that most people wouldn't notice.