There are numerous slang terms and phrases that are used in place of "scare shitless." Some of the most commonly used synonyms include "freak out," "terrify," "spook," "startle," "petrify," "frighten," "panic," and "shock." Other slang terms that can be used include "scare the bejesus out of," "scare the daylights out of," "scare the living daylights out of," "scare the pants off," and "scare someone silly." Regardless of the exact phrase used, the meaning remains the same: to be extremely frightened by something unexpected or frightening.