My friends and I used to do this when we were bored. Basically, show a picture and ask a question. Easy ideas for photo trivia are high magnification macros. However, don't neglect simple things like plant or animal identification, or in the case below, name the location from where a common landscape is taken. Be sure to provide hints (e.g., what lens used) for perspective.
Here's an easy one:
Where was I in Chicago when I took this picture (Canon 10D, 28mm, f9.5, 1/350s)?
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