The evidence leads me to believe that people really are uneducated
about this, and the problem seems to go deep and have many roots.
First there's the general lack of half-decent sex education in public
schools in the U.S. Then there's the fact that women's bodies are
used and abused in advertisements and magazines. (This says nothing
about the vulva in particular, but if the rest of the woman's body is
supposed to be tiny...)
Speaking as a heterosexual man, I've
seen plenty of vulvae, of a wide variety of shapes, colors, and
sizes, and they're all beautiful.
And I thought most
heterosexual men would agree with me.
Anyway, I really can't
blame you for not speaking out against what your friends said about
large clitorises, since it's hard to speak up when you're
outnumbered. But if I were you, I'd talk to your friends individually
and inform them that some women do have large clitorises, and that
those women would feel extremely hurt to hear what your friends had
said.
If they're still willing to listen, you might
show them this website. If not... well, I wouldn't call them my
friends if they weren't willing to listen to my opinion.