on their best behavior

idiom

: exhibiting proper behavior

The children were all on their best behavior at the museum.

Examples of on their best behavior in a Sentence

Recent Examples on the Web

In others, family members have to be on their best behavior to make it through without some kind of contretemps. —Belinda Luscombe, TIME, 9 Apr. 2024

So for now, at least on a recent weeknight in Deptford, parents, grandparents and friends, were on their best behavior. —Dan Gelston, Anchorage Daily News, 9 June 2023

Despite a tense atmosphere, both the Americans and the Europeans were on their best behavior in Munich: both U.S. Vice President Mike Pence and NATO Secretary General Jens Stoltenberg expressed their continued commitment to the alliance. —Jonathan Eyal, Foreign Affairs, 2 Mar. 2017

No doubt kids will be on their best behavior in the days leading up to St. Nicholas Day after being threatened with something like that. —Sucheta Rawal, Travel + Leisure, 29 Oct. 2023

By that point, coaches gathered both units and implored them to keep it cordial, and for the second half of practice, both teams were on their best behavior. —Chris Bumbaca, USA TODAY, 17 Aug. 2023

While George and Charlotte were on their best behavior in the exclusive enclosure over the weekend, Wimbledon has had a tricky history regarding kids in the Royal Box. Can't get enough of PEOPLE's Royals coverage? —Janine Henni, Peoplemag, 18 July 2023

See His Cutest Faces at King Charles' Birthday Parade The Prince and Princess of Wales’ children seemed to be on their best behavior during the festive flypast, where the Red Arrows Aerobatic Team of the Royal Air Force soared overhead. —Janine Henni, Peoplemag, 20 June 2023

The Tribune cautioned that locals should be on their best behavior when the prince arrived on Sept. 21, 1860. —Kori Rumore, Chicago Tribune, 4 May 2023