When you have messed up really bad and your boyfriend/girlfriend is to the point of something drastic. Such as breaking up. Time to step it up, asshole and put on the pants.
Person: I messed up big time. My girlfriend is going to be so upset. I think she is going to break up with me!
Person 2: You know what time it is then
Person 1: No, What?!
Person 2: It's Apology Pants Time!