The whole song is built on one silly, clever pun. "Ya solo eres mi ex" (now you're just my ex), and then every next line starts with ex: "Mi experiencia más desagradable" (my most unpleasant experience), "La exclusiva dueña de mis males" (the exclusive owner of my troubles), "Mi excelente excusa pa una peda" (my excellent excuse for a bender). It is a breakup song that sounds like it is having fun with its own bitterness.
A few gems for learners: "peda" is Mexican slang for a drinking session, and "pa" is the spoken short form of para. "Ya ni borracho quiero que vuelvas" (not even drunk do I want you back) is about as final as it gets. And "Contigo ya dos veces no tropiezo" (I won't trip twice with you) plays on the saying about not tripping over the same stone twice. Then, right at the end, comes the sting: "Y te llamabas... Chiquitita" (and your name was... Chiquitita), a sweet nickname meaning little one, delivered like he barely remembers it.