Apparently, Hardee's found that "a majority of Americans (60%) say the day after Daylight Saving Time, Monday, March 9 is the worst Monday of the year." (because you end up losing an hour i.e. less sleep) And so, the phrase and accompanying free biscuit sandwich, are meant to make the day at least a little bit better.
Hardee's Sausage Biscuit features a grilled sausage patty between two halves of a signature Made From Scratch Biscuit.
Photo via Hardee's.