Alcohol use is a known risk factor for acquiring or transmitting sexually-transmitted infections, like HIV. But why? The obvious answer for most is that alcohol impairs your ability to make sound decisions. But, in a study we recently published in the Journal of American College Health, we showed that the tendency to drink for specific reasons could increase risk for having more casual sexual partnerships than others. Specifically, we found that drinking "to have more fun," and "to be more sociable" may lead some to drink more heavily, which in turn, may lead to engaging in casual sex more often.