i guess im lucky cuz im a girl, so it usually takes them a good 5 seconds (and funny facial expressions) before they get it through their head that i actually ride, and by that time they have forgotten how dangerous bikes are and are thinking about how hot it is
on a more serious note, i usually just smile sweetly and say 'yessir, donchoo worry bout me sir."
if it's a bitchy lady giving me airs though, i will just flat out ignore her.