Papa Johns Pizza is currently running one of the cleverest Facebook promotions I’ve seen.  Between now and December 1, if you sign up to be a fan of of Papa Johns on Facebook you will receive a coupon for a free medium pizza (fineprint: you must first purchase a pizza online, which insinuates this is really a buy one get one free type of things).

The promotion appears to be working, as Papa Johns has gone from 10,000 fans to 168,509 fans in a matter of days.

Not bad, particularly when you consider the coupon isn’t any different from the ones the pizza chain mails out and offers on their website every day.