As many are well aware, Costco is a membership warehouse store. When you purchase your goods, instead of bagging your purchases with bags, they recycle boxes. Smart in that Costco saves on hauling away a bunch of cardboard and leave it up to the buyers to dispose of. Anyway, we made a Costco run and got a bunch of 1/4 boxes (sort of). This gives new found excitement for the puppies. Honestly, I think they are bored cooped up in the pen. So we put some of these boxes in there and they are for now briefly entertained.
As you can see they have taken to this particular box. In fact while some puppies like to relax in this milk box, others like to sit on it - king or queen of the hill if you will. Further, when they are up there, they're territorial and try to dissuade their siblings from joining them.