There was a big kerfuffle around the alcoholic beverage called Four Loko, which was a fruity tasting beverage with caffeine and alcohol. Young people wound up in the hospital with severe alcohol poisoning. it was a bad situation, and the mixture of alcohol and caffeine was implicated.
The effect of Four Loko might actually be more a product of the novel, fruity flavors and colors than the caffeine, according to an article in Perspectives on Psychological Science:
We may surmise that the Four Loko experience for many undergraduates would involve receiving alcohol in an unusual context. As noted by Bruni (2010), Four Loko—a “biliously colored,” sweet, synthetically fruity beverage—is an unusual medium for alcohol: “It’s a malt liquor in confectionary drag.” The results of studies of situational-specificity of tolerance suggest that Four Loko and similar drinks are especially effective as intoxicants because these beverages provide an unusual context for the intoxicating drug that they deliver.