Act Up

The idiom act up is applied to people, especially children, machinery and electronics; and medical conditions. The word act is used to mean behave in a certain way or “to do” while up serves as a negative intensifier, so that this idiom (phrasal verb) means to behave or act badly.

Meaning of Idiom ‘Act Up’ (phrasal verb)

1. To act up, usually in regards to children, means to behave badly or cause trouble.

2. In regards to machinery or electronics, to malfunction or to operate abnormally.

3. In regards to medical conditions and their symptoms, to act up means to become active. Often used in regards to allergies. ^{1 2}

Want to see more videos from Idioms.Online? Subscribe to our YouTube channel!

Sentence Examples

“If you children keep acting up, we are not going to go to the amusement park.”

“I don’t know what’s wrong with my dog, he never acts up like this. Maybe he is sick.”

“My computer acted up yesterday so I wasn’t able to get my report finished.”

“The car is acting up so I’m going to have to take a cab to work today.”

“Can you open this jar?” asked Mom. “My arthritis is acting up.”

“When my allergies act up I usually just take one pill, but today was a two-pill day!”

“Michele is not a man. He’s a little boy ok. And his parents happen to be going through a really bad divorce and thats why he’s acting up.” — Hancock (2008)

“Fifteen people in this house, and only you have to make trouble.” “I’m getting dumped on.” “You’re the only one acting up. Now get upstairs.” — Home Alone (1990)

“Sorry I didn’t grab you down at the station. Damn wagon’s been acting up. Miss Elizabeth won’t spend the money to get her fixed.” — Dark Shadows (2012)

“Sheriff, where are you headed?” “There’s trouble down a dry creek. Bad Bill’s been acting up again.” — Rango (2011)

“It’s dusty, my hay fever’s acting up and you always break something.” — The Goonies (1985)

Origin

Used since around 1900. ³

More Idioms Starting with A

• Add Fuel to the Fire
• All Tuckered Out
• Are You Writing a Book?
• Army Brat
• And How

More Act Idioms

• Get Your Act Together
• Clean Up Your Act
• Act of God, an

More Up Idioms

• Drive Someone Up the Wall
• Go Belly Up
• Get Your Dander Up
• Screw UP
• Jig is Up, the

References

1. Heacock, Paul. Cambridge Dictionary of American Idioms. Cambridge: Cambridge UP, 2010.
2. Bengelsdorf, Peter. Idioms in the News – 1,000 Phrases, Real Examples. N.p.: Amz Digital Services, 2012.
3. Ammer, Christine. American Heritage Dictionary of Idioms. Boston: Houghton Mifflin Harcourt, 2013.