When I first rode with the local bike shop, I was riding my mountain bike.
The owner told me to leave early with the fat bottom girls.

I couldn't believe what he said. I looked at him askance. "Tha whaaat?"

What he really said was "The flat-bar'd girls" meaning, the girls on mountain or fitness bikes who were leaving early because of having fatter tires / slower bikes.

His accent really threw me off.