A woman discovered, that one of the kids had bange

A woman discovered, that one of the kids had banged the kitchen-doorway with a skateboard on the way out to play. The splinters were catching on her clothes, each time out.
She decided to buy a file to smooth it out.
Thinking that she might be taken advantage of if she let on that she
was indeed a novice, she made a determined effort to look and sound as
if she knew what she was doing. Completing her first group of
purchases she took them to the clerk at the counter and looking behind
him she discovered she hadn't bought any files. She pointed to one and
said "May I have one of those ?"

The clerk, unsure of what she was indicating said, "What... one of
those bastards ?"

Without a pause, she said, "Yeah ! And ya better give me a few of
those Son-of-a-Bitches next to 'em too."