Black-belt

[rebbonk]

On the way home from the pub last night, I found the instructor from my karate club at the pavement edge, struggling to get to his feet.

He had a broken nose, two black eyes and a broken arm.

I helped him up and said, "Wow, mate, I thought you were a black belt."

He said, "I am,

Spoiler:

but it doesn't work against cars."