A very sharp buxom young teaching colleague received a similar comment from some pupils, her reply was classic, Don't send a boy to do a man's job! The pupil was so embarrassed and his friends thought it was hilarious, he never did it again!
On another occasion when she had reprimanded some pupil he threatened her, I'll report you, I'll tell them you locked me in the stock room and made me have sex with you! Her reply was You should be so bloody lucky!
I used to be so envious of her quick wit and putdowns.