Knock Knock, Whose There

Knockers–Door Knockers

Knockers- Women’s Breasts

Tommy knocker (folklore)

A mythical creature, like a brownie or leprechaun, believed to live in underground tunnels; later associated with dead miners.

Knocked up–Being with child, pregnant

Knocked down-to strike to the ground with or as if with a sharp blow: fell. 2: to dispose of (an item) to a bidder at an auction sale. 3: to take apart: disassemble.

Knock-off-a copy that sells for less than the original broadly : a copy or imitation of someone or something popular. To stop doing something.  To do something hurriedly or routinely. To kill or rob.

Knock around or about-Travel without a specific purpose.  Happened to be present.  Spend time with somebody.