I told a guy in the Dunkin Donuts line at DCA that my mom had signed a permission slip for me to be a pilot so it was okay.
I think he saw through my sarcasm and said he didn't mean anything by it and that he thought it was great I was so driven that I could get hired at a young age. He said "That's really cool" about a half dozen times.
I too am 23 and don't even blink at the (old) folks that comment at my youthful appearance anymore. I normally just tell them I'd be flying C-130s in Afghanistan right now if my eyes had cooperated and they stand down.