look up any word, like blumpkin:
 
1.
The period between 5:45 and 6:45 in which ladies and gentlemen are encouraged to remove their trousers and pantaloons and relish in festive celebration.
No Pants 'O Clock may take place during the AM or the PM.
Guys! It's 6:30! We're missing No Pants 'O Clock!
by Spudmonkey May 25, 2006
 
2.
Any time in which not wearing pants is socially acceptable. Usually takes place in the evening, with preference occurring after eight pm.
Is your room mate not wearing pants?

Yes, after all, it's No Pants O'Clock in our living room after eight.
by missiworld October 09, 2011