Economist Greg Mankiw proposes a bet with New York Times columnist/hack Paul Krugman.

Team Obama says that real GDP in 2013 will be 15.6 percent above real GDP in 2008. (That number comes from compounding their predicted growth rates for these five years.) So, Paul, are you willing to wager that the economy will meet or exceed this benchmark?

That sort of four-year expansion wouldn't necessarily be unprecedented, but it would be quite impressive -- especially considering that this is the "worst economy since the Great Depression."

An additional note:

Krugman characterizes Mankiw's skepticism as somehow "evil." That's par for the course for Krugman, who can't simply disagree, he must demonize.