That’s just a high school term for a low-pitched female voice that I detest.
As for “Joe Pesci is not a countertenor. Michael Jackson is one, as well as Tiny Tim,” you have a point. Maybe Joe Pesci is kind of like Justin Bieber, only his voice is fully developed. He’s, like, right between a tenor and a countertenor. As for Tiny Tim, his natural voice was not a countertenor; he just sang entirely in his falsetto.