best behavior

If you can do the cauliflower, you better be on your best behavior.’

This theater was already on display in the 1936 Olympic games, when all the “Juden unerwüscht” signs disappeared, and Nazi bullyboys were on their best behavior.

Not all were on their best behavior.

I was told that if I was on my best behavior, I would go to the sought-after public elementary school down the street and finally get my own room.

They should have been on their best behavior on Tuesday to avoid any glimmer of impropriety.