Alternate scenario: She's an average girl with average likelihood to f**k on the first date, but she wrote that description as (what she thinks is) a funny flirty bit of text. And then she'll be surprised that all the responses are from guys who ONLY want sex. Plus it'll be their fault for not knowing she was just joking.
You're 20. It's not a long sexual career, unless you started banging dudes before you were even born.