I mean, if you made me guess the sex of the person involved, I would certainly suspect it was a boy. Mischief of this kind tends to be more popular among boys. But a joke like this isn't intrinsically sexist, or anti-girl, or silencing of female voices
(Obviously, it's good if genuine sexism is halted in coed classrooms so that both boys and girls can learn.)
(Obviously, it's good if genuine sexism is halted in coed classrooms so that both boys and girls can learn.)