Every so often the thunder would crash, and they would involuntarily jump.

He jumped involuntarily, then waited a moment and opened his eyes.

Morris's quiet voice startled her and she jumped involuntarily.

Everybody involuntarily jumped, the sound was so startling, although expected.

She jumped back involuntarily as the toy, or whatever it was, headed for the two men.

I involuntarily jumped, nearly losing my balance, and he ordered me in a loud imperative voice to look.

He closed the door behind him so hard it slammed loud enough to make both of them jump involuntarily.

The question came so abruptly, and from such an unexpected spot, that everyone on the bridge jumped involuntarily.

Then he jumped involuntarily as she twisted into the co-pilot's seat beside him.

She involuntarily jumped and turned, relief washing over her features.