be on (one's) best behavior



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be on (one's) best behavior

To be very polite or exercise exceptionally good manners. Primarily heard in US. Now, you kids must be on your best behavior for your Auntie this weekend! Good morning, class. I hope everyone was on their best behavior for the substitute teacher yesterday.
See also: behavior, on

Common Names:

NameGenderPronouncedUsage
GiorgiaJOR-jahItalian
SophySO-feeEnglish (Rare)
Andor (1)-Norwegian
Rajkumari-Indian, Hindi
Tamid-Arabic
Ayumuah-yoo-mooJapanese