How to Use act up in a Sentence

act up

verb
  • The kid acts up, the dad disciplines him and mom just sends a sorry text.
    — Hannah Sacks, PEOPLE, 22 Sep. 2025
  • Nobody's that good an actor to keep this act up for 50 years.
    — Daniela Avila, Peoplemag, 27 June 2024
  • Mature parents do not slap their children across the face for acting up.
    — Jeanne Phillips, Mercury News, 25 Sep. 2025
  • Excess dust may also cause your allergies to act up.
    — Madeline Buiano, Martha Stewart, 22 Feb. 2026
  • Sturm said his back started acting up after the team’s first practice.
    — Michael Russo, New York Times, 1 Oct. 2025
  • The capsule’s toilet is already acting up.
    — Marcia Dunn, Chicago Tribune, 2 Apr. 2026
  • Soon after her descent, the walls of the cave grow so wet that the Wi-Fi router begins to act up.
    — D. T. Max, The New Yorker, 21 Jan. 2024
  • Her pain can act up suddenly and seemingly comes without rhyme or reason.
    — Matthew Futterman, The Athletic, 7 Mar. 2025
  • Johnson, who struggles with a neuroma, swears by her Oofos mules to keep it from acting up.
    — Jennifer Heimlich, SELF, 29 Aug. 2025
  • Some of the biggest names in Hollywood weren’t afraid to act up on Friday night.
    — Matt Donnelly, Variety, 10 Jan. 2026
  • After lunch, Streisand was ready to relax and needed to stretch her back, which lately has been acting up.
    — Wesley Morris, New York Times, 7 Nov. 2023
  • Then the engine started acting up, which would have cost up to $10,000 to fix.
    — Shannon Pettypiece, NBC news, 22 Sep. 2025
  • All that lightweight foam underfoot can help keep your arches from acting up when your mileage starts to climb on long-distance runs.
    — Jennifer Heimlich, SELF, 27 Nov. 2024
  • Bruce, as the stunt shark built to menace them is nicknamed, is acting up and delaying the acting itself.
    — Christopher Smith, Oc Register, 10 Mar. 2026
  • Advertisement If your computer is acting up, that’s a big sign that things are not right.
    — Jim Rossman, Dallas News, 30 July 2023
  • But if your transmission acts up or your steering system goes haywire, car insurance won't help you.
    — Alora Bopray, USA Today, 5 Dec. 2025
  • Currently, Screen Time often acts up and just cuts off access to all apps, whether it’s supposed to or not.
    — Tyler Hayes, PC Magazine, 9 June 2026
  • The resident followed this act up by going back inside and reemerging with a rifle, Evans said.
    — Timia Cobb breaking News Reporter, Dallas Morning News, 15 Jan. 2026
  • What would cleaning their act up entail beyond the firings of Wilkinson and Golub?
    — Bill Oram, oregonlive, 9 Oct. 2022
  • As such, when a supporting character acts up, Dreux or Alyssa can rib them, but not too viciously.
    — Fred Topel, Deadline, 17 Jan. 2025
  • Meanwhile, the guests, who have literally just arrived five minutes ago, are already acting up.
    — Rafaela Bassili, Vulture, 10 Mar. 2026
  • The biggest trophy of the night is for video of the year, which originally saw 16 acts up for the coveted belt buckle.
    — Sadie Bell, Peoplemag, 6 Apr. 2024
  • If your trackpad is acting up, keyboard shortcuts can keep you productive without fighting the cursor.
    — Ken Colburn, AZCentral.com, 19 Jan. 2026
  • Sahl was known to devour numerous newspapers and magazines every day to keep his topical act up-to-date.
    — Dennis McLellan, Los Angeles Times, 26 Oct. 2021
  • The instrument’s dust cover has been acting up since January 6.
    — Amanda Kooser, Forbes, 14 Feb. 2024
  • That shank was a shocker, and perhaps more concerning was Woods saying his back was acting up int the final hour, leading to the shank.
    — Doug Ferguson, USA TODAY, 16 Feb. 2024
  • Likewise, when the young men started acting up, Josephine Holt took a keen interest in her newspaper.
    — Literary Hub, 21 Jan. 2026
  • In November of last year, the car started acting up — the transmission seemed to have failed after just a few months of ownership.
    — Andy Kalmowitz / Jalopnik, Quartz, 11 June 2024
  • The black flies are not the only troublesome creature acting up during the unseasonably warm weather.
    — Clara Harter, Los Angeles Times, 28 Mar. 2026
  • Even these little figures of speech can reflect how, in frustrating situations, you might be tempted to blame your nerves for acting up—or stress out about how to calm them down.
    — Maggie O'Neill, SELF, 31 Mar. 2023

Some of these examples are programmatically compiled from various online sources to illustrate current usage of the word 'act up.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

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