Fun problem to work out on a Friday afternoon. I'll publish the answer in about a week but feel free to
email me your guesses or ask any questions.
Me and my partner have a dinner party and invite 4 couples. As people arrive, some hug, some kiss and some shake hands. Once all couples have arrived, I assemble everyone and ask each person how many people they shook hands with. Everyone gives a different answer. Given that no one shakes hands with themselves, their partner or anyone twice, how many people did I shake hands with?