Take a shot whenever you phaselock the wrong target.
Take a sip every time you miss a point blank shot as Gaige because your accuracy is shot to hell after racking up hundreds of Anarchy stacks. But only if you're suicidal.
Take a shot every time Deathtrap runs out of HP instead of timing out.
Take a sip every time you use your action skill.
Take another every time you die in the middle of it.
Take a sip every time Silence The Voices causes you to hit yourself in the face. Take a shot if it hits you more than twice in a row, 1-in-8 chance of self-injury be damned. Just chug if it's more than three times in a row, you'll probably need it.
Take a sip every time you accidentally start Gunzerking with a weapon combination you didn't mean to bring out, like a Dahl sniper rifle and a Hyperion pistol.