Rata inmunda is Spanish for filthy rat, a common insult used in Spanish-speaking countries for someone seen as low, sneaky or untrustworthy. The elongated spelling inmundaaa reflects how the word is shouted in the clip, with the final vowel stretched for comic emphasis rather than as a formal pronunciation. Short insult clips like this travel well on soundboards and in short-form video because they need no context to be understood by Spanish speakers, and the exaggerated delivery keeps the insult feeling playful instead of serious, which is why creators keep reusing it for betrayals and pranks.