During ww2, in Finnish long range patrol detachments, there was a custom of one of the men carving a large wooden d**do out of a thick branch. The more f**ked up shape the better.
During preparation he would then hide it inside one of his comrades' rucksack without the owner knowing. Once noticing the wooden d**do, the owner of the rucksack would then quietly transfer it over to someone else's rucksack whenever possible, typically when the detachment would camp out deep behind Russian lines.
This way the d**do would make the rounds through everyone, of course also the leader, before being returned back to finnish soil. It was essential that no one would say anything when they found the tool in their sack