I had three older sisters. I picked up jump rope rhymes.

I think boys, even at an age when they couldn't possibly do anything about it, would use more creativity for dirty jokes and whatnot. The older guys who rode my school bus when I was in the early grade school years were pretty inventive. I took mental notes. Yeah, offhand I'd say the received wisdom tended to be off-color. Not that I didn't learn that from my sisters as well.