From Shotgun Shuffling
The Ratches are an unlikely hybrid of cockroaches and rats created by the questionable housekeeping practices at "O'Jacks" fast food place. They can fly and the bug spray does nothing. Mankind has met their inevitable doom.
While not employees as such, their impact on the lives of those who worked at the store where they were created can't be underestimated. See, "the day we were all fired." KK described them an "Omega Pestilence" in what may or may not have been a direct quote from the Health Department who responded to a report of the Ratches, and this has become an affectionate name for the Ratches in the comments.
Apparently Cinn requested Ratches for Christmas and Ellie obtained some for her with the excuse that she wanted them to keep her tarantula company. During Black Friday shopping she released Ratchantulas and seemed to enjoy the chaos she was causing and was shown in the next strip to have taken advantage of the panic to obtain "abandoned" purchases from fleeing shoppers. It isn't yet clear if Cinn deliberately set out to create Ratchantulas or if they were just a happy, to her, coincidence. All that's currently known is that she released them at or near Burlington Coat Factory during Black Friday.