domestic flights, almost no chance unless your parents are cool. International is another story tho, lufthansa for example gives out unlimited free beer, like you can ask at different times and its the same as getting a soda or water. I think air france is free also, and they gave free drinks to me on the way back (paris to montreal), but because we flew into canada, that may have changed things. The lufthansa flights where I have gotten free alcohol were newark to frankfurt, and dusseldorf to st. petersburg (and back). In a few days I will be able to update this and tell you if they serve to minors on US bound flights