knock on wood
US /nɑk ɑn wʊd/
UK /nɑk ɑn wʊd/

1.
敲敲木头, 避邪
said to ward off bad luck, often while knocking on a wooden object
:
•
I haven't had a cold all winter, knock on wood.
我整个冬天都没感冒,敲敲木头。
•
Our business has been doing great this year, knock on wood.
我们公司今年业绩很好,敲敲木头。