jump out of one's skin
Be extremely startled or frightened. For example, When he crept up on me so quietly, I nearly jumped out of my skin. [Early 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.