working the room blue

Please help me.
I’m having a little with the jargon of my own field, and none of my collegues can help.
I do stand-up comedy. In comedy, the term “blue” refers to vulgar humor (potty jokes, sex jokes, etc.). All comics know this term, but no one I’ve spoken to seems to know how it originated.

Why are dirty jokes called “blue”?

Maybe because they violate - or used to violate, since they don’t exist as much anymore - Blue Laws?

I meant to write “I’m having a little TROUBLE with the jargon of my own field.”
For some reason I can’t edit my posts.
Anyway, just trying to provide clarity.

bienville, only moderators can edit posts. It’s not just you.

Anything to do with the blue light, traditionally (?) used to highlight a stripper’s act.

I wonder if it has anything to do with bad language turning the air blue—you know, like “cursing a blue streak?”

Seem to remember a theory that it goes back to censors crossing out the mucky bits in scripts with a blue pencil -
Don’t know if it predates “The Cheeky Chappie” Max Miller -

Well, the Oxford English Dictionary doesn’t say exactly how the word “blue” came to be used in this way, but it does provide quotations that suggest a nineteenth-century origin.

and

That’s for England, at least. I’m not sure about the US.