He's a human capable of reproduction and judging by the number of children he has had ample opportunities to do so. Most humans of reproductive age like sex, and those who have a lot of it tend to like it more. It's always been the funniest and most relatable topic for any group of adults to joke about.

With that said, if you think Elon Musk is a role model that guides your conscience, the north of your moral compass... Dude, he's just an obscenely rich guy. And I guarantee you almost every teen and even younger children in the world already knows what those words mean or is capable of finding out in short order. Even prepubescent children make jokes about genitalia and sex and anything else that adults take seriously. If you want to know all the most offensive and/or raunchiest jokes, just ask a late elementary or middle schooler.