I'd be nice to him, pet him, 'good boy, but you've got to go home, let's go' and 'dad stern talk' him home. You'll have to do it a while, but he'll grow out of it. Meanwhile, sort of enjoy him without the responsibility or expense of ownership.
YMMV, as I have two dogs, and have to talk myself out of more...
Knowing this man hater, her dog is a *****. The same should apply though. Ill give that a try but Ill have to get a collar and leash on it. I'm sure it's a female. Her name is Rosie.