Knocks your socks off

To completely surprise or please you very much

The magazine is beautiful and combines color and unusual design in a way that "knocks your socks off".

I'd knock the back out of that!

Said about a sexually appealing woman, with whom you would be very eager to have sex.

To explain the metaphor: you may be a little too vigorous, and push your penis all the way through her, hence, knocking the back out of her... Obviously not physically possible, but a good, although rather crude, metaphor

Guy A: Phwoar, Check her out, what a stunner!
Guy B: God yeah, I'd knock the back out of that!

knock his dick in the dirt

To "knock his/their dick in the dirt" indicates a humiliating or violent setback has been suffered, often in sports.

Knock his dick in the dirt

That sack sure knocked their dick in the dirt!

I'd knock the dust off of that

I'd fuck that old lady

When you see an hot old lady .
You can say " I'd knock the dust off of that."

knock-down-drag-out

prolonged, violent, and unrestrained

They got into a knock-down-drag-out brawl over the stupidest thing.

Mr Hankey is Knocking on the Door

Means to have to defecate or have a bowel movement or to have to take a dump. Mainly used for an emergency situation, where the movement in imminent, but can be used for any announcement of your condition.

Remember that jalepeno burrito I had earlier, with the ice cream sundae and Heinekins for dessert? Well, Mr Hankey is knocking on the door about now!!

I've been sick all day, and I think Mr Hankey is knocking on the door again.

knock your cock off

To be so surprised/astonished/amazed/intense that your cock is knocked off.

That tentacle porn will knock your cock off.