"Murphy's law"

While my dog Pippa and I were out enjoying the cold, yet sunny weather, we came across Murphy. Where my dog is complete anti-social (as in ignoring everything and everybody but the ball-bearer) when I bring a tennis ball whenever we go for a walk, Murphy had his own special toy. After having experienced the "joy" of wood splinters in his mouth and throat it was decided that all in all wooden sticks were not safe. One day Murphy came across this "teat" (used to feed calves) and he has adopted that in the same way my Pippa has her tennis balls.
Both dogs wanted to play, but Murphy kept seeing his "teat" despite futile attempts to hide it, but it was a fun moment. And maybe a good alternative for some other dogs?