I was getting ready to pay at a restaurant when the cashier asked me if I wanted the senior discount. At the time I was not near the age to qualify, I was just prematurely gray. I was not offended in the least. I said of course I want the discount. Could have been offended but saving $$ trumped that.
Same thing happened to me in Macdonald's about 10 years ago, I supose when your 15 everybody over 30 looks old. I stayed calm and demanded to see the manager adding that I'd never been so insulted in my life. I was with friends who were pissing themselves, within about 30 seconds the whole place knew what had occurred...much merriment