Is it permissible to describe a teacher as "accursed"—with the intention of joking without his knowledge—after addressing him as "My Esteemed Professor"?

There is no harm for a student in saying "Sayyidi" (my master/sir) to his Muslim teacher, as the Prophet (peace and blessings be upon him) addressed some of his companions with this title. However, for a student to say "Do not be hateful or accursed" is inappropriate, due to its lack of manners and the offense it contains. The teacher deserves respect, gratitude, and prayers.