そのティーンは、彼女が初めてお尻で犯されることを、聞かずに知らなかったのです。

She certainly imagined anal defloration differently! Maybe the scared girl also wanted to remain a virgin in the asshole? We don't know for sure, but it's too late now anyway. The guy just stuck his hard cock in her back door without asking and you'll see how surprised she was by her pained looks!