Doggie Bungee Toy
For me, playing with dogs is like playing with kids: I'm good for about 7 minutes before I need a nap. Particularly when they have boundless energy for tugging or saddling you up like a horse and riding around on your back. This Doggie Bungee Toy solves at least one of those problems (and I think I might be able to convince my girlfriend's 4-year-old nephew that it's more fun to play with than I am too). The toy's 8' bungee and protective sheathing loop around a tree limb / trunk / secure post, and then clips to a toy connector line and your choice of attachable toy. The listed set includes a large hanging ball knot.
Obviously, when dogs jump or tug on the toy the bungee cord's stretch-and-retract nature will make for some nonstop action as it snaps back, bounces, and flies all catawampus as soon as they let go. It's interactive play that lets Suzy Lou Snuffleupagus spaz out for as long as she wants, not just as long as your rotator cuff and tolerance for dog drool can handle. The Doggie Bungee Toy is basically your iFetch for the backyard.