He hurt his knuckles while playing football.

The knuckle draggers were causing a ruckus at the party.

I don't want to get into a fight with him, or else I might end up with a couple of knuckle sandwiches.

Let's have a pea-knuckle to settle this argument.

I found a jar full of pea-knuckles in the pantry.

The knuckle-draggers were causing a ruckus at the party.

He knuckled under to their demands.

He always knuckles under to his boss's demands.

I saw a group of knuckle-scrapers at the construction site.

He is such a knuckle-scraper, always getting into fights.