I'm not saying a 7-yr-old would know the term, but we do live in an age when 7-year-old like that little girl last night are quite poised. When they hit puberty (which people who study these things say is happening earlier than in past generations), they begin to learn terms stronger than ballsy pretty quickly.
Yep. I remember my first time riding a public school bus. I was six or seven. I learned just about every slang and curse there is in about 30 minutes.
The Gherkin's 19 and she's never heard a tame word like "ballsy"?? I'm not buying it.