Freakonomics Quiz: Twice Is Enough

Last week something that has never happened to me before in my life, occurred twice, independently, in two days.

What was it? First correct answer in the comments section gets Freakonomics swag.

Although that is a meager set of hints, I’ve found that no matter how hard the quiz, Freakonomics blog readers can answer just about any question within an hour. I’ll be curious to see what happens on this one.

Update: Here is the answer to this contest.