We also have a new segment from the Argentine telenovela, Verano Eterno posted for your edification. Amid the rapid banter, we heard:
Yo hoy me voy a dormir a mi casa, tranquilito, pero vos mañana salís conmigo. -Ni loca.
Today I'm going to go home to sleep, laying low, but tomorrow you go out with me. -No way.
Captions 67-69, Verano Eterno - Fiesta Grande - Part 13Play Caption
"Ni loco" or "Ni loca" (for a female speaker) is basically a short-hand way to say "Not even if I were crazy," "No way" or "Not on your life."
Here are a few more short but colorful "ni" expressions that mean essentially the same thing:
Ni en broma diga una cosa así.
Not even jokingly should you say such a thing.
Caption 91, Muñeca Brava - 41 La Fiesta - Part 6Play Caption
Ni en pedo vuelvo a esa casa ¿sabe?
Not even drunk will I go back to that house, you know?
Caption 30, Muñeca Brava - 7 El poema - Part 8Play Caption
Ni en broma
Not even as a joke / No way
Ni en pedo
Not even drunk / No way
Finally, there are some other phrases we thought of where "ni" + "que" means something like "como si" in Spanish. "Ni que" might be translated into English as "it's as if" or (with a negative slant) "it's not like." Here are three examples:
Ni que fuera el diablo en persona.
It's not like he is the devil incarnate.
Caption 35, El Ausente - Acto 3 - Part 3Play Caption
¿Por qué me gritas? ¡Ni que fuera sordo!
Why do you yell at me? It's as if (you think) I'm deaf!
Ni que fuera adivino, para saber lo que piensas.
It's not like I'm a fortune teller who knows what you're thinking about.