This isn't a stupid question at all, just cute. I rode my spyder to the International Motorcycle Show in DC in January. A little boy was walking with his mom. I'd guess he was about 4 years old. He said, "You rode that? I didn't know girls could ride motorcycles?!"
I do get the "do you like that" or "how do you like that?" question.
A lot of people ask about the licensing, Maryland requires a motorcycle license but you can take the test on a three wheel and then be limited to only three wheels. I have a full license so, I usually tell them that and point out that I choose to ride the spyder because it's fun, has storage, and great extra features (heated handgrips, radio, ipod, etc.
So, mostly I get the "how fast does it go?", "does it lean?", "do you like it?" and "how much is it?". Not too many stupid questions, just repetitive. I have had a couple people (usually wearing a biker shirt) say "I wouldn't ride one of those!" but then, I've also had people wearing biker shirts say, "It doesn't matter what you ride as long as you're having fun."
So, I try to always be nice to the people asking questions. People are still wary about things that are different. And, because the spyder attracts so much attention perhaps some of those other bike riders are jealous.