This is either a great trademark or a not so great trademark, depending on the quality of the applicant's cakes. Section 2(e)(1) of the Trademark Act prohibits registration on the Principal Register of new trademarks that are "merely descriptive." Section 1209.01(b) of the TMEP states that a mark is considered merely descriptive "if it describes an ingredient, quality, characteristic, function, feature, purpose, or use of the specified goods or services."
On the other hand, arbitrary words and phrases are great trademarks. Section 1209.01(a) of the TMEP defines an arbitrary mark as a mark that "comprise[s] words that are in common linguistic use but, when used to identify particular goods or services, do not suggest or describe a significant ingredient, quality, or characteristic of the goods or services..."
So, depending upon whether the applicant's cakes are really good or really bad, the filed mark either describes a quality or characteristic of the specified goods (making it merely descriptive) or does not describe a quality or characteristic of the goods (possibly making it arbitrary). At any rate, it is a perplexing (or genius?) marketing choice by the applicant.
So which is it? I guess we need to wait and taste the applicant's goods to find out.
1/19/2018 - turns out, I recently had the opportunity to try the applicant's rum cake! Despite the name, it is not "Really Bad" but in fact really good. Guess it isn't merely descriptive after all...