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

Days before the wedding, Bones joked that Stanley and Eller would need to be on their best behavior to be included in the special day. —Tamara Palmer, Peoplemag, 26 May 2024

There is a difference between letting the best in people express itself and keeping people on their best behavior. —James Poniewozik, New York Times, 24 May 2024

New Yorkers weren’t exactly on their best behavior, either, with one dude holding up an image on his phone of a potato (presumably referencing the Irish Potato Famine). —David MacK, Rolling Stone, 16 May 2024

Usually the executives at these soirees are on their best behavior, especially when the discussion is on the record, like this one. —Steven Levy, WIRED, 12 Apr. 2024

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