Kongs are the best! My dogs only get them when they are full of stuff, because, Shelby won't play with them otherwise, and, Beethoven has had some resource guarding issues, and I'm worried he'd get possessive over them, and hurt my cats if they were left out (I'm doing NILIF with him for that reason). I hold the Kongs for them, or, if they are full of kibble (which is tons of fun), I take them into a room away from cats, and put them on the floor. It's hysterical to watch. I think I enjoy them as much as the dogs do LOL.
So far, I've only stuffed them with peanut butter, and kibble. What else makes good Kong stuffing?