Agüita'o is a colloquial term, a shortened form of agüitado, which means 'down', 'sad', or 'bummed out'. It's a less common, more informal way to express sadness or being disheartened, making it interesting for learners.
In the song, Junior H sings, "No ando enamorado, mucho menos agüita'o" (I'm not in love, much less bummed out). This phrase highlights the protagonist's detached state, emphasizing that he's not only free from romantic entanglements but also from the emotional lows that often accompany them, preferring to stay in his dream-like escape.
Mexican artist Junior H sets up a hazy escape hatch from heartbreak in "Atrapado En Un Sueño". He finds himself stuck in a strange dream, floating high above the ground far away from reality. He is not in a rush to wake up, either. The dream gives him peace because nobody is around to hurt him or boss him around: "Me siento bien / Porque estoy solo, solo sin nadie / Ni un solo ser / Que me diga qué puedo y no hacer" ("I feel good / Because I'm alone, alone with nobody / Not a single being / To tell me what I can and cannot do"). Down in the real world, someone crushed his chest, leaving him pretty cynical about romance. He bluntly writes off modern dating with the line "Las mujeres ya no aman / Solo buscan la lana" ("Women don't love anymore / They only look for cash"), where the Mexican slang lana literally means "wool" but translates directly to cash or money.
Instead of dealing with that mess, he chooses seclusion and self-medication. He insists he is neither in love nor down in the dumps: "No ando enamorado / Mucho menos agüita'o" ("I'm not in love / Much less bummed out"). Notice the word agüita'o (a shortened, sung form of agüitado), which is everyday Mexican slang for feeling sad, mopey, or downcast. To keep that gloom away, he asks to roll "unos gallos pa' el volado" ("some joints for the flight") so he can stay bien guisa'o (slang here for being totally baked). Even though shadowy figures linger in the background trying to block his exit, he is perfectly content to drift in this fog for the next ten years while the rest of the world falls apart.