Season 3 · Episode 8
Futurama
Dr. Zoidberg reunites with his uncle, silent hologram star Harold Zoid, and the two of them set out to make a movie together. They cast the temperamental Calculon in the lead role, who demands an Oscar for his performance, but the movie doesn't go over well with audiences.

A fixed phrase drawn from the old telegram/postal convention where the recipient pays on collection. Used here to signal that a written request comes with a financial expectation attached, delivered with comic irony.
A species-specific variant of the common Latin American expression 'llevarlo en la sangre' (to have it in the blood). Used to say someone has a natural, innate gift for something. The humor here comes from substituting 'valvas' (shells/valves) for 'sangre' to suit the speaker's non-human biology.
Not slang on its own, but used here as a weasel word, a deliberate hedge that lets a speaker walk back a near-promise. When someone says something is 'prácticamente' guaranteed, they leave themselves a linguistic escape hatch. Common in informal persuasion and sales talk.
When said with ironic intonation after being pressured into an unfavorable agreement, 'gran negocio' works as sarcasm. The literal meaning is 'great business/deal', but the context flips it into a complaint or resigned joke.