I'm glad I re-read this post. I am going to try a new approach next time I get the three boys comments because none of mine fit the full stereotypes either.
I think I will try saying (and this is inspired from Hotdogs post but shortened for convenience)
"Let me let you in on a secret, the stereotypes just aren't true," I think that should work. Can't wait to try it and I hope I remember to. Tips on how to improve it welcome.