Hmmm...I've been lucky then. I've had a beer or two on about half-a-dozen SQ flights aged 15 to 17. I guess it helped to look older as I was formally dressed while non-revving under staff tickets
I also did 3 under-age flights in the cockpit jumpseat while non-revving and the crew even apologised saying that no alcohol could be served while I was seated in the cockpit.
OT: My parents subscribed to the idea that if I'm going to be drinking underage anyway, they'd rather have me drinking at home under their supervision. I've been having the occasional wine with dinner since the age of 12 - it sure helped build up resistance and I haven't turned out to be an alcoholic.....yet 
Originally Posted by kpc
One day, you will find it a compliment to be asked your age before you are served alcohol
Funnily enough, I've only been carded on the ground after I hit my mid-twenties. It definitely feels like a compliment then