Well an ounce of Vodka is, what, 70 cals... a little more and most alcohol is about that I think, I drink vodka and soda water. Some will say tonic water, but tonic water has sugar in it. And wine is lighter in calories than some of the special drinks. If you like whiskey you could do it with diet cola. You can squeeze lemon or lime to anything, add a couple cherries, or have them stick a splash of juice in anything with soda water...
On days when I know I'm gonna consume more calories than a normal day, I will put a good wook out in ahead of time!