Where does the saying "knock your pipe out" come from

[laura65]

Where does the saying "knock your pipe out" come from

[Quizmonster]

The only times I have ever seen or heard of someone "knocking his pipe out", it was used literally...ie a pipe-smoker was cleaning his pipe out in preparation for refilling it. In doing so, he would knock it against an ashtray if indoors or against his heel if outdoors to clear it of the used-up tobacco in it. I've done it many a time myself in my bad old smoking-days!

[Quizmonster]

It seems knock your pipe out can also mean put yourself to too much bother. As such, it would seem to be just a variant of knock yourself out, which meant the same thing...ie put too much effort into doing something.
Having said that, I have no idea where the pipe came from!

[shunter09]

In my experience, it's used to describe a man who is masturbating, that is looking to clean his 'pipe' meaning penis, before going on a date with a sexy lady. i..e knocking one out.

I've heard it used several times by recruitment consultants in the pub as a kind of filthy banter. Especially those who unsuccessfully appeared on master chef.