scare someone shitless

US /skɛr ˈsʌmˌwʌn ˈʃɪtˌlɛs/
UK /skɛr ˈsʌmˌwʌn ˈʃɪtˌlɛs/
"scare someone shitless" picture
1.

to frighten someone very badly

:
The sudden loud noise scared me shitless.
Watching that horror movie last night scared him shitless.