I disagree that "saturday night" ever means anything other than the literal meaning of the nighttime of the day of saturday.
You can argue that there's a connotative association with the phrase. Sure. Just like "beach weather", or "blizzard conditions". But that doesn't make "saturday night" special in any way.
You can argue that there's a connotative association with the phrase. Sure. Just like "beach weather", or "blizzard conditions". But that doesn't make "saturday night" special in any way.