act up

verb

1. informal,  (intr, adverb) to behave in a troublesome way

   the engine began to act up when we were miles from anywhere

Idioms and Phrases

Misbehave. For example, With an inexperienced rider, this horse always acts up . [c. 1900]

Malfunction, as in I'm not sure what's wrong with my car, but the transmission is acting up . In both usages up means “abnormally.”

Example Sentences

On the morning of our departure, our van battery acts up and the motor won’t start.

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"When people hear leaders using that language it allows the average Joe Bloggs to act up and that's why we had the race riots of Summer 2024," she added.

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RCA still sees plenty of room for Sleep Token and its ilk to win freshly curious audiences, and conjure even more metal acts up the charts.

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I started acting up simply to keep myself occupied.

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In the early years, he said, he acted up, raking up disciplinary infractions that landed him in solitary confinement.

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