Green & Tonic is a startup that works with bar owners to reduce waste and energy use, helping with everything from biodegradable straws to composting -- hey! The G&T firm (gotta say, it's a catchy name) is also into local and sustainable adult bevies. Tomorrow, the Green & Tonic folks are putting on what they're calling a Zerowasted Pub Crawl to the following "green" bars: Doc's Clock, Casanova Lounge, and Elixir. Expect discounted drinks, a green auction, and a sustainable scavenger hunt. It starts at Doc's Clock (2575 Mission at 22nd St.) at 4 p.m., Saturday, September 19, heads to Casanova (527 Valencia at 16th St.) at 5:30, then on to Elixir (3200 16th St. at Guerrero) at 7 p.m. Feel better already? Wait'll you get a few sustainable drinks in you.