hold a gun to someone's head
Exert pressure on someone, as in How could I refuse when she was holding a gun to my head? This hyperbolic expression dates from the first half of the 1900s. Also see at gunpoint; hold one's feet to the fire.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.