Open the coop door and say, ladies, this is Mister Roo....Mister Roo, these are the ladies...Dora, Flora, Nora, Cora, Lora, Zora, Mrs. Pepper, Mrs. Omnivore, and baby kate. Mr. Roo will be staying with us a while, I am sure you will show him your hospitality. Mr. Roo if there is anything I can get for you, don't be afraid to call.
Make him look really impressive by tossing in some cracked corn or another treat right after adding him to the pen. If he's a good husband type he'll start buk-buk-bukking to the hens as if he just cooked it himself. They'll think he's Mr Wonderful for showing up with such a tasty treat to share.
If you have a small flock (those were the days) you can put the roo and a bowl of yogurt in with him. You will be amazed at what happens next. The roo will call the hens and they will instantly love him and want him and be with him.