shrug one's shoulders
Show indecision or indifference, as in When I asked her if she minded staying home, she just shrugged her shoulders. This redundant idiom—shrug means “to raise and contract the shoulders”—dates from about 1450.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.