Stick that new shoe in your mouth

So my wife was at the store getting some new running shoes and the guy helping her happened to be black. She saw on his name tag that his name was Ryan Brookes so in trying to make conversation she said "Brookes, that's my son's middle name"

He and the other guy working there said, "Oh that is a cool middle name." Then the other guy said jokingly, "so is his first name Ryan?"

My wife replied, "no- and he isn't black either".

I guess it was a funny joke in her head. I don't get it and neither did the guys at the store.