scared out of one's wits

Example: “The thunderclap scared the dog out of his wits.”

Origin: Built on a construction English uses for every kind of overwhelming emotion — out of one's mind, out of one's senses, beside oneself — all of which describe the same thing: a feeling strong enough to displace the person from their own faculties, leaving the reason somewhere outside the body it belongs to. The idea is old and was once meant more literally than it now sounds, and Greek preserves it plainly in ekstasis, standing outside oneself, the ancestor of the English word ecstasy. "Wits" here has its older sense of the mental faculties collectively. What the phrase claims is specific and physiological: fear has not merely upset the capacity to think but has expelled it, which is a recognizable description of what acute panic actually does.