Going to the Upper East Side...?

If you are under 21, you can totally forget about drinking in a bar or restaurant in NYC....totally forget about it. The establishment can lose its liquor license, and that license cost them at least $100,000. So they're not going to take any kind of chance on serving anyone who can not doubly prove they're of legal age to drink. As a matter of fact, some places have their own age restriction, i.e., having to prove that you're at least 25 years old, or some other age beyond 21.