The debate revolves around the colors of the Decepticon Mini-Cassettes, Rumble and Frenzy. It was Hasbro's intent that Rumble be black and red, and Frenzy be two shades of blue. These color schemes are used in the toyline, Marvel Comics and many storybooks and ancillary media from the early years of Generation 1, and naturally, it was intended for the cartoon series to render the characters in this manner as well (as proven by the show's production bible, which identifies Rumble as the "red robot"). However, as a result of some unspecified error somewhere in production, the two robots had their color schemes swapped, leaving the animated incarnation of Rumble blue, and Frenzy red.
Due to the widespread recognition the cartoon received, the concept of Rumble as the blue robot was ingrained into the minds of many viewers. As such, years later, fans would argue vehemently (though often tongue-in-cheek) over which coloration was "correct", based mainly on their personal preference for the cartoon or comic.
The FIRRIB movement was codified by a MUSH user and cartoon fan named Scott Wells in 1994, who coined the acronym FIRRIB. The FIRRIB idea quickly caught on with other cartoon fans on alt.toys.transformers, frequently appearing in signature files; its counterpoint, the comic- and toy-based FIBRIR, soon appeared as well. After endless discussion threads fueled by little more than personal preference, the subject eventually landed in the group's FAQ file as a do-not-ask question.
The Japanese dub of the Generation 1 cartoon rectified the error, making the animation match the toys by simply switching the characters' names around.
As later incarnations of the characters draw on both the cartoon and toys as influences, the waters have become muddier still:
Items in the following table are listed in release order. E.g., the original toys came first.
Original toys Blue Red
Marvel comics Blue Red
US cartoon Red Blue
Japanese cartoon Blue Red
Generation 2 toys Purple Red on white3
Dreamwave comics Blue Red
Devil's Due comics Red Blue
Alternators toys None Red
Music Label earphones Blue Red
Person 2: What?
Person 1: Frenzy Is Blue Rumble Is Red!