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

Example Sentences

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

From Los Angeles Times

I told her the camera is going to be constantly running, so when she’s acting up — and I wanted to open the film with that — she knew that was being recorded.

From Salon

One testified that Adams said he would never “take a kid’s word” over that of a staffer; another said Adams matter-of-factly passed along the advice he had received about beating kids if they acted up.

From Seattle Times

Second, the few who do act up end up arrested, despite Trump's insinuations to the contrary.

From Salon

It seems like it would be easy to just put a pill into a treat and then you don’t really have to worry about them acting up.

From Salon