cutoff time 

The period of time after a set time at which it is no longer socially acceptable to call someone. Usually around 9-10 o'clock. Only to be violated in periods of extreme urgency. Originally coined by Larry David on, "Curb Your Enthusiasm"

Person 1: Oh shit, I forget to tell my friend that he has to meet me at noon tomorrow.

Person 2: Too late now, it's past the cutoff time.

cutoff time by Specialnator July 23, 2010

Cut Off Time

The point reached in the day when it's too late to get any from the opposite sex. Usually applies after a long day at work.

Boy: Girl, I know you alone tonight.
Girl: It's cut off time. Hit me on the weekend.

Cut Off Time by CreeperStash January 28, 2008