Make/borrow/whatever a magic + swords world, isekai people periodically.
They can:
Prank otherworlders (Gender Bender, etc)
Watch people's reactions when they're not the first otherworlder in this world ("No! I can't be the smartest!")
Ship the otherworlder with somebody, and place bets on it...
A single sneeze was all it took. A [World Event], started by one given the name *beep* by the whole world. A blessing for some, a curse for some.
The starting point could be called strategic and disastrous at the same time. Strategic, because in the most populated country in the world, it can...