"You're not Seamus McFly. You look like him though, 'specially wearin' that dog-ugly hat! You kin to that hay barber?"
—Buford Tannen asking Marty if he's related to Seamus McFly

"You kin to that hay barber?" was a saying used by Buford Tannen in 1885.

When Marty entered the Palace Saloon, Buford mistook Marty for Seamus McFly because of the hat he wore which had been given to him by Seamus. He noticed his facial similarities to him, and asked him if he was related to Seamus, referring him as a "hay barber", due to the fact that he was a farmer.

Marty later stated that his name was "Clint Eastwood ", averting his question. (Ironically, Seamus was Marty's great-great-grandfather.)