The idea is really simple, make your slave cum in a condom, then have them take the condom and slip it over their tongue so their tongue is swimming in their cum. Make sure they bite down gently on their tongue to keep the condom in place, not only to ensure a cummy tongue but for safety so the condom stays in place. Also for added humiliation and safety make the slave keep their tongue out of their mouth the entire time.
Make them wear it as long as you want, make fun of them during this, ignore them, do homework do as you please, or you can turn it into a game and time them trying to slurp it out of the condom! Make them do it again next time until you think think they did it quick enough!
Have fun everyone!