Do I look like this guy? Apparently I do, because it seems like I get asked this question ALL THE TIME! It's happened to me at Costco, at Blockbuster, at the Costco gas station, Albertson's, etc. It's not as though I am dressed for the part. I never wear those vests that grocery stores put on their people, nor am I standing behind the counter, nor am I not filling up my car with gas after putting my credit card through the reader. I generally think that I have a reasonable tolerance of stupidity, but these just get me going.
I think there are a couple of reasons why they bug me so much. One is the inherent age bias that I choose to see in it. If I was ten years older, I'll bet I wouldn't get this question. By the same token, if I was 40 years older, I'd probably get this question still. Just because I'm young doesn't mean that I don't have the requisite school and/or social standing to have moved past those jobs.
Will I beat anybody up over this? I doubt it. Do I wish that I had a great Bill Engvall "Here's Your Sign" comment to say to those who asked me these? You bet. Alas, I don't think I've had the requisite humour training to figure that one out yet.