Meaning of “shake sb up” - Learner’s Dictionary

shake sb up

phrasal verb with shake uk us /ʃeɪk/ verb (past tense shook, past participle shaken)

If an unpleasant experience shakes someone up, it makes them feel shocked and upset:

The accident really shook him up.

(Definition of “shake sb up” from the Cambridge Learner’s Dictionary © Cambridge University Press)