be on (your) best behaviour

British & Australian, American & Australian

to behave very well, usually because you are in an important or formal situation.

Now children, I want you all to be on your best behaviour when grandma arrives.

• word to the wise is sufficient.
• work against the clock
• work arse off
• work a treat
• work backside off
• work both ways
• work fingers to the bone
• work guts out
• work hand in glove with
• work hand in glove with someone
• work hand in glove with something
• work into the ground
• work its magic
• work like a charm
• work like a dog
• work like a trojan
• work like clockwork
• work like magic
• work magic
• work miracles
• work out
• work out something
• works
• work socks off
• work the problem