Midsummer quiz? What were some of the questions?
The theme was "general ignorance" - but translated into Swedish O-kunskap ("kunskap" meaning knowledge and with the O having nothing to do with orienteering). The answer to every question had to start or end with an O or contain the letter O.
One example you can use as a brain teaser was to mention at least six capitals in the World starting or ending with an O.
Other questions were to mention plants (flowers, trees…) beginning with an O or chemical elements containing the letter O in their (Swedish) name.