Today (April 15th, 2013) is McDonald’s Tax Relief Day: Buy One, Get One for 1 Cent. Buy one Quarter Pounder with cheese or Big Mac at regular price and get one more of the same sandwich for 1 cent. The offer is valid only at participating McDonald’s locations.
This promotion ran during 2013, 2014, 2015, 2016, and 2017. Who knows, they might bring it back!