I've never heard this and there were plenty of girls on IRC

Well if you've never heard that old joke, then clearly it can't ever have existed, right?

Oh wait:

> Welcome to the Internet, where the men are men, the women are men, and the kids are cops.

https://news.ycombinator.com/item?id=1546789

I picked this instance of course because it was said on HN, but it was a dead horse even in 2010.

Of course it was, but that's not what we're talking about. The link I chose was just the arbitrary one I picked from the google results.

Personally I remember hearing that joke in the 90s. If you want a different example, here's a variant from 2001: http://www.bash.org/?2832

Note that this one ends with "but some of the men are really women"; it's already old and well-known enough in '01 that people are modifying it for meta-humor.