I knew someone who would list his dog’s name as the first name. When someone called (and his kids had a lot of fun with this) and asked if Izzy Jones, or whatever, was in, the response was “He’s out in the back yard pooping,” or “He’s sleeping under the dining room table.”
That’s great! Sounds like something one of my brothers would have done.
Years ago, when one had to pay to have an unlisted number, we listed our number with the dog’s name. But we never thought to have fun with like you described.