English Dictionary

act up

verb

(intransitive, idiomatic) To misbehave; to cause trouble. / (intransitive, idiomatic) To perform the duties of an appointment senior to that actually held; to deputise for a superior.

My computer always acts up when I'm in the middle of an important task.

意味（1）

(intransitive, idiomatic) To misbehave; to cause trouble.

My allergies act up during hay fever season.

意味（2）

(intransitive, idiomatic) To perform the duties of an appointment senior to that actually held; to deputise for a superior.

Acting up is always recommended when you find yourself under a new boss.