on (your) best behavior

not causing any difficulties.

The two candidates were on their best behavior, giving serious answers to questions from a group of citizens.

Usage notes: usually used to refer to children, but also often used to describe the actions of adults in uncomfortable situations

• have your eye on
• have your eye on someone
• have your eye on something
• have your feet on the ground
• have your finger on the button
• have your finger on the pulse
• have your fingers in the till
• have your guts for garters
• have your hand in the till
• have your hands full
• have your head in the clouds
• have your head screwed on
• have your head screwed on right
• have your head screwed on the right way
• have your head stuck up arse
• have your head stuck up your arse
• have your head up arse
• have your head up your arse
• have your heart set on
• have your heart set on doing something
• have your heart set on something
• have your knife into
• have your knife into someone
• have your mind on
• have your mind on something