Jump out of your skin

Jump out of your (my, his, her, rtc.)  skin: assustar-se ou ficar chocado repentinamente, levar um susto

“Luke was watching the clouds pass in front of the moon when I quietly snuck up behind him and tapped him on the shoulder. He screamed and nearly jumped out of his skin!”

“Ollie didn't know I was making some toast, and when it suddenly popped up just as he was walking past he jumped out of his skin. It was really funny!” (www.englishclub.com)

 fonte: http://aguadedentadura.com