For me, the most asked question... "How fast does that thing go?" no matter which bike I've ever been on. As if I'm going to lay down on the tank and do a full Bonneville speed run to test her out.
On the airhead people used to say "Wow, I didn't know BMW made motorcycles".
One guy at a stop light..."Hey, what's that big thing down by your foot?"
"Uhm, a cylinder."
"Oh. Is there one on the other side?"
"Uhm, no. This is a five hundred. The one thousands have one on each side."