Una desilusión, una canción

Used as a mildly insulting but often playful term for someone seen as useless or annoying. Its meaning is not obvious from its parts and it has an old-fashioned, theatrical flavor that makes it sound funny rather than truly harsh.

The verb 'ilusión' in Argentine Spanish carries the sense of hopeful excitement or wishful thinking rather than a false perception, so 'hacerse ilusiones' means to build up unrealistic expectations. The emotional weight is stronger than a literal reading suggests.

Used to signal that a matter or situation is unfinished and will be returned to. 'Pendiente' literally means hanging or pending, but the full fixed phrase implies an emotional or relational loose end, not just an administrative one.

Short for 'ni loca lo haría'. Used by a female speaker (or about a female subject) to express emphatic, absolute refusal. The male equivalent is 'ni loco'. The idiomatic force is much stronger than a literal reading of 'not even crazy' suggests.

Literally 'skull/cranium'. Used as a compliment meaning someone is exceptionally clever or creative. The meaning is entirely non-compositional.