Quote from Joey in The One Where Ross Dates a Student
Rachel: Who wrote it? Ross: Oh, I wish I knew, but the evaluations are all anonymous. Joey: Hey, do you still have their exams? Ross: Yeah. Joey: Because you could just match the evaluation to the exam with the same handwriting and, boom, there's your admirer. Chandler: A hot girl's at stake, and all of a sudden he's Rain Man.