Well this might be expencive so use the cheep diapers. Take several ( around 10) and put different spice and kitchen items, like cloves ground up, soy sauce.....whatever.

Then number them and have everybody smell them and try to guess what's in the diaper. It's fun when you get stuff like A1 seeing everybody's face.

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"I've seen a look in dogs' eyes, a quickly vanishing look of amazed contempt, and I am convinced that basically dogs think humans are nuts." - John Steinbeck