If I was standing, my knees would be knocking together.
You could tell by the way his tiny knees knocked together.
Their volunteers worked out of the same office and sometimes knocked on doors together.
I heard her teeth knock together, like my father's when the fever took him.
The man's face had gone chalk white, his knees knocked together.
He called lawyers to a private conference and "heads were knocked together," one lawyer said.
Mallory didn't think she'd be able to walk without her knees knocking together again.
Having no timber to knock together, we must make a metal frame.
They were soon knocking about the galley together, making sandwiches.
"I'm having enough trouble keeping my knees from knocking together, little say trying to wear a smile."