While on the Concours:
"Hey, nice Beemer!" My response is usually "Well, it is a K bike, if K is for Kawasaki."
While on the Ural:
" Who makes a "Why-pan?" Damn Cyrillic alphabet tank badges . . .
My all-time favorite:
"What do you do if it rains?"
Most of the dumb stuff I hear is ATTGAT related rather than bike related though.
"You wouldn't be riding a motorcycle if you weren't an optimist."
- Matthew Crawford
2005 Ural Tourist, 2000 Kawasaki W650