upside the head
Against the side of someone's head, as in With those nightsticks the police are known for knocking suspects upside the head. [Slang; second half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.