British, American & Australian, American

something that you say when you want your luck or a good situation to continue.

It's been fine all week and, touch wood, it'll stay fine for the weekend.

We haven't had any problems with the car so far, knock on wood.

• wheel and deal
• wheeler-dealer
• wheel has come full circle.
• wheel has turned full circle.
• wheeling and dealing
• wheels are turning
• when all is said and done
• when back is turned
• when hell freezes over
• When in Rome .
• When in Rome do as the Romans do.
• when it comes to the crunch
• when push comes to shove
• when ship comes in
• when someone's back is turned
• when someone sneezes, someone catches a cold
• when someone sneezes, something catches a cold
• when someone was a mere twinkle in father's eye
• when someone was a mere twinkle in their father's eye
• when someone was a twinkle in father's eye
• when someone was a twinkle in their father's eye
• when something sneezes, someone catches a cold
• when something sneezes, something catches a cold
• When the cat's away .
• When the cat's away the mice will play.