I have a drink once in a while and try to drink something relatively low in calories - usually vodka. It's only about 60 calories per ounce. I also work it into my calorie total for that day.
Keep in mind, though, that a jigger is 1 1/2 ounces (which is a standard bar measure) and very very few bartenders actually measure what they pour so you're probably getting more than 1 ounce...
but if it's something you enjoy - definitely work it into yur day