I make a lot of jokes. About women, blacks, jews, ... also, about men, whites, programmers. I don't discriminate; I make fun of everything and everyone!

The existence of dirty joke books that include every possible person and group doesn't make it a good idea to bring any one of them up at a professional event.

It's a natural thing to take a dump. But you most certainly don't to that in the audience of a Python conference presentation. Even if it is harmless, because you used your own bucket and cleaned up after yourself. Even if you and your family usually leave the door open when using the toilet at home. Even if there are some hilarious poop jokes.

If people can control when they use the toilet, when they eat, when they have sex -- all much more important parts of people's nature than telling sexist jokes -- then I see no good reason why they aren't also able to control the use of sexist language in the workplace.

(There are rare exceptions. Some people have fecal incontinence, and can't control when they defecate. Others have mental problems which prevent them from controlling what they say. Dealing with those exceptions is far outside this current debate.)

Now, there may be other reasons (though I can't think of any) which justify sexist behavior in a work environment, or for that matter justify making fun of someone who doesn't want to be made fun of. But an appeal to natural behaviors does not provide that justification.

And please do note that you said "harmless fun between two people that don't share that trait", but as this was a public meeting, where the conversation was easily overheard by others, your situation does not apply because more than two people were involved.