Lisa & her male friend Michael are discussing her meeting with young man.
Lisa: The other day at the car wash a young man looked me up and down and asked me if I was a natural blond.
Michael: What did you say?
Lisa: I looked him straight in the eye and I said: "Well, let's say if I stood on my head, I'd be a natural brunette with lovely breath."
Michael: You didn't.(with laughs)
Lisa: I did.(with laughs)
What is the meaning of Lisa's words in this context?
I used Strong format on the words which i didn't understand.