Ask for a glass of tap water and tip $10
You'll likely get free non-alcoholic drinks free the rest of the night.
I'm 10 years sober... I started the tip thing because I didn't think it was fair to go to an establishment, listen to the music, enjoy the scenery, and pay nothing to anybody. Especially because I cannot emotionally justify spending $7 on a diet pepsi that's 60% ice.
Didn't really realize it was going to happen, but it seems like staff really appreciates that and then treats you really kind in turn.