I'm going to make you watch how your boyfriend slobbers all over this giant slab of man meat. You can sit in the corner and see how enthusiastically he struggles to take me down his throat, how he moans so much louder with me in his mouth than he ever has for you. Listen to how he begs for me inside his hole. Your smaller cock can't compete with me.

Be a good cuckold -- just shut up and let your boyfriend enjoy the best cock he's had in years. You can clean up the cummy mess afterwards.