Papelón is a colloquial term in many Spanish-speaking countries, particularly in the Southern Cone, that refers to a big mess, a scandal, or an embarrassing situation. It's a more colorful and expressive word than simply saying "problema" (problem).
In the song, the lyric "Quiero que me expliques este papelón" (I want you to explain this mess to me) perfectly captures the frustration and disbelief of the speaker regarding a chaotic or shameful situation that has unfolded. It's a word that adds a strong emotional punch and is less common than everyday vocabulary, making it memorable.
No Te Va Gustar, from Uruguay, brings us "Halcones Y Payasos" [Hawks and Clowns], a song that feels like a blunt conversation with someone who's really messed up. The speaker is clearly frustrated, saying, "Han pasado cosas y esto es un montón" [Things have happened and this is a lot] and demanding an explanation for the "papelón" [mess/scandal]. It seems like this person has made some bad choices, perhaps selling their soul or losing their way, becoming "solo gris" [just grey] with no options left.
The lyrics paint a picture of betrayal and regret. The person being addressed has let someone else take over, giving them too much power: "Le abriste la puerta de tu gran mansión / Era un pajarito y ahora es un halcón" [You opened the door to your big mansion / It was a little bird and now it's a hawk]. This new "hawk" has completely taken over, leaving the original person with no control, not even "derecho ni a mover sus cajas" [the right to move their boxes]. The speaker has seen this pattern before, calling it "Todo el tiempo las mismas canciones" [All the time the same songs], and they're ready for the "payaso servil" [servile clown] and "mala gente, los mismos traidores" [bad people, the same traitors] to finally run away.