Frozen bananas + Kong!
Just thought i'd share. In my never-ending quest to find ways to keep the pup busy.. I tried freezing some bananas when they were on their last leg of being "good" (peel them first of course). Broke one in half and stuffed it into a Kong toy with a little bit sticking out. He was at that thing for a good 30-40 minutes! And 30-40 minutes with Konig is a godsend.