What told that there were "three holes to choose from" when having sex with a girl, I interpreted this to mean that women had three vaginas, and the important thing to learn was *which* vagina to penetrate. I had no idea what would happen if you got the wrong one, but I imagined it was like something out of Indiana Jones.

Often, boys will believe that girls only have one hole - a universal hole for everything. A hole from which drops piss that stinks a bit like poo. And poo that has the golden glisten of piss and babies.
As our understanding inevitablly developed, we discovered that the front hole had ANOTHER two holes in it, like women were a damn Mandlebrot set of ever more specific holes.
One boy who clung to the single-hole theory also believed that a vibrator was a kind of footspa, and that you could ask your hairdresser for a blowjob.

I had to explain to our year's alpha male about the trinity of lady holes. I did do slowly, and with the aid of some meticulous diagrams in the back of my chemistry book.
He'd been having sex for two years, but was surprisingly placid throughout my lesson. When I'd finished, he simply looked at me and said 'well, my cat doesn't have three holes'.