There is the neighborhood schnauzer, and even thought their sizes reversed with time, they still travel in the same circles.
There are Easter guests and school pals,
and the neighborhood Corgi, who likes a good game of "Ha-ha I have your tennis ball and you don't."
Finally, there is the elite TBFC (Tennis Ball Fanatics Club); they play many games - which could go on all day, every day, 24/7. These are expert dogs that Dover can learn from!