Nope, I don't remember!
But as much as my boys enjoy it, it's not necessarily something to encourage - or so say some dog experts. Some say that it promotes aggressive/dominant behaviour. I'm on the fence on that.
When I do play tug with my boys, when play is finished, I always "win".
I also use it as a training tool. When I say "leave it", they do.
They love tug...they will tug with me, and they will tug with each other...their favourite tug toy is the Skineez Duck. With a neck,tail, two legs and two wings, there is lots to latch onto. Plus the squeaker also encourages them to play as well.
If you want to play tug, I recommend the Skineez product line (p.s. we also have a now very sad looking squirrel which remains one of their favourites)