Or perhaps students who were being paid by Red Bull. Most things in life are rarely free. Hate to sound like some conspiracy crackpot or something, but given this experience, if it is a marketing ploy, they're banking that because you got one for free, you're going to be more likely to buy one in the future. It's not a big deal or anything, I was just wondering if your school was allowing/aware of this. Unless you're in college, in which case I'd be more wary of the folks hawking credit cards than the nice girls giving out free soda.