My wife and I went to a dinner party attended by four other married couples.
When everyone arrived and greeted each other, a bunch of handshakes occurred.
No one shook their own hand, no one shook their spouse's hand, and no two
people shook hands with each other more than once.  Afterward, I asked the
other nine people (including my wife) how many hands they had shaken.  To my
surprise, they all gave different numerical answers.  So... how many hands
did my wife shake? 

TIP: There are no tricks here -- i.e, no one lied, no one was an amputee, etc.
This is just pure logic.