Every time I teach microeconomics, I assign Robert Frank's The Economic Naturalist and have students come up with their own question and answer it. Most of their have their own questions ready but for those that want something different, here're some questions I've found myself asking.
Why does the Trader Joe's in Foggy Bottom (and other stores like Best Buy) use a queue system but the one in Fairfax (as well as stores like Safeway) does not?
Why do AC units and fans have the "high" option next to the "off" option which then decreases (OFF, HIGH, MED, LOW) while stoves use a gradual increase (OFF, LOW, MED, HIGH)?
Why do restaurants give away free bread, which crowds out room for a paying dessert?
Why does popcorn costs so much at the movies (and no, it's not because they have a monopoly on popcorn)?
Why do different movies cost the same amount no matter how crappy or good they are?