Hmm. I want to say something mysterious, like what happened to some sailing ship that disappeared, or something like that to know what happened.
Or there's some guy that buried a treasure in Missouri and left the location in a cryptogram that hasn't been solved to this day.
But I think it would be most fun to witness Apollo 11's first space walk. Niel be talking about "one small step for man" and I just walk up applauding. And then ask for a lift home.