Absurdo translates to "absurd" or "ridiculous." It's an interesting word because it describes something that is illogical or nonsensical, and it's not as commonly featured in song lyrics as more direct emotional words.
In "Pídeme," the singer uses it when he says, "Yo sé que tal vez esto te suene absurdo" (I know that maybe this sounds absurd to you). He's acknowledging that his deep devotion and willingness to do anything for his beloved, even asking for the most expensive gift in the world, might seem over-the-top or irrational to her, yet he means it sincerely. This adds a layer of self-awareness and dramatic flair to his declaration of love.
Grupo Legítimo's "Pídeme" is a super direct and passionate song all about unconditional love and devotion. The singer is basically saying, "Ask me for anything!" He's willing to do almost anything for the person he loves.
He offers to do things like "Pídeme la luna para ir por ella" [Ask me for the moon, so I can go get it] or even "escribir tu nombre en medio de la luna" [write your name in the middle of the moon]. He'll give the "regalo más caro del mundo" [most expensive gift in the world]. But there's one thing he absolutely cannot do: "Pero no me pidas que yo me olvide de ti" [But don't ask me to forget you]. That's the one impossible request, showing just how deeply he feels!