It isn't often you see the words "love", "romance", and "Federal Reserve" in the same sentence.

But on Friday, the US central bank and many economists who spend countless hours monitoring its decisions began their Valentine's Day flirtations a bit early.

It started with Justin Wolfers, an economist at the University of Pennsylvania, who tweeted this morning: "You're my long-run target; my nominal anchor" - with the attached hashtag, #FedValentines.

For those who aren't steeped in FedSpeak, what Wolfers was referring to was the Fed's inflation benchmarks.

Within minutes, some top economists in the United States had chimed in with their own take on Cupid.

They included Austan Goolsbee, who was previously President Barack Obama's top economist and is now professor of economics at University of Chicago Booth School of Business.

Some of the Fed's regional arms - the San Francisco Fed, Philadelphia Fed and Atlanta Fed - weighed in, as did a number of academics and journalists.

"I am surprised by all of this," Wolfers said in a phone interview. "My Twitter stream is filled with geeks, nerds and policy wonks and I thought we'd have nerdy fun. It ended up far more viral than I had anticipated. It went from completely nerdy to sometimes dirty tweets."

The only unofficial rule was that the tweets had to be written using the Fed's often obscure terminology. The resulting declarations ranged from pure romance to cute overtures and racier fare.