My niece, aged about 7, after looking at a magazine left lying about:
Niece: "Mummy - what's a c*ndom?"
My sister: (Gives very well thought out and perfectly executed s*x talk, with talk of safe s*x)
Niece: (Thinks for a moment). "Well, why would they have chocolate ones?"
I think this is where my sister, who had been so cool with all of it, changed the subject rapidly!