scare/frighten someone witless
US /skɛr/ˈfraɪtən ˈsʌmˌwʌn ˈwɪtlɪs/
UK /skɛr/ˈfraɪtən ˈsʌmˌwʌn ˈwɪtlɪs/

1.
把某人吓得魂不附体, 把某人吓得不知所措
to frighten someone so much that they are unable to think clearly or act sensibly
:
•
The sudden loud noise scared him witless.
突如其来的巨响把他吓得魂不附体。
•
The ghost story frightened the children witless.
那个鬼故事把孩子们吓得魂不附体。