The Chicago Cubs have been in the news lately relating to its legal battle over its new advertising signs with the surrounding rooftop bars and investors. However, the Chicago Cubs have also initiated a brand new lawsuit against Whole Foods Marked IP LP.

Whole Foods recently applied for the word mark “LITTLE CUBBIES” for use in connection with breakfast cereals. On April 2, 2015, the Chicago Cubs launched a Notice of Opposition—a proceeding where a third-party can attempt to stop a trademark from becoming federally registered—citing a plethora of its federal registrations as grounds for the Opposition.

As you probably guessed, the Chicago Cubs do not have a registration that covers “breakfast cereals,” although they do have a registration for the word “CUBBIES.” The Chicago Cubs claim the word “LITTLE” in Whole Foods’ application is not sufficient to distinguish the mark from the Chicago Cubs’ registered trademarks. As such, the Chicago Cubs believe Whole Foods’ use of the “LITTLE CUBBIES” mark in connection with bear head cereal will cause confusion in the marketplace—the standard for trademark infringement.

There are a couple of lessons to be learned from this. First, when adopting trademarks for use in connection with your products, it is important to think outside the box for purposes of clearing your mark. This is perfectly demonstrated by the Chicago Cubs case. One would think that “breakfast cereal” is sufficiently different from any use of the “CUBBIES” mark by the Chicago Cubs. And while this may eventually be found the case by the Trademark Trial and Appeal Board, Whole Foods is now required to fight what will most likely be a costly legal battle to prove this.

Second, when selecting and adopting trademarks, you should be careful about adopting marks that are anywhere close to what could be considered a “famous” mark. The term “famous” has a specific legal connotation in trademark law, which is outside the scope of this particular post. However, marks owned by the National Football League, National Baseball League, Nike, or similar companies should be considered as off-limits to third parties. These companies are notorious for strong enforcement policies and have the financial backing to defend their marks to the fullest extent of the law. Importantly, for marks that are considered “famous,” any use of the mark—even on completely unrelated goods—can be an infringement of the mark.

Lesson of the day: be careful in choosing marks that are even tangentially related to a national sports team’s mark.