For many years, we had a lady at our stamp club give a stamp quiz, once per year. Her name is Helen and it was simply "Helen's Stamp Quiz" on the agenda.
Her quiz was 20 questions. They went from difficult to impossible. Most people got four or five right answers. I got eleven, one year, but it was luck! Many people complained that her quiz was too difficult. You had to pretty much be a specialist in a particular area to get the questin answered correctly.
It was all fun.
In response to those who complained about the difficulty of the quiz... I suggested the Vice-President's quiz. It would include such questions as:
1. What is the face value of the 1851 3d Beaver?
2. What colour is the green Ram Tank on the 14-cent War Effort stamp?
3. What spacecraft is depicted on the U.S. Space Shuttle stamp?
Got any more?

David