darse un susto increíble have a terrible fright (fear); be scared silly (fear); be scared stiff (fear); be scared to death (fear); be scared out of one's wits (fear)
dar un susto a alguien give someone a fright (fear); scare someone (fear); frighten someone (fear)
dar un susto increíble a alguien scare someone to death (fear); scare the life out of someone (fear); scare the wits out of someone (fear); scare someone silly (fear)