the name for the delayed hangover you get when you get so drunk, you wake up drunk, and then the next day is when your hangover kicks in.
"Hello. Yeh, I'm not coming to work today, I have a Monday Morning Hangover..."
When a girl tells you Sunday that she is leaving you, so you get extremely drunk that night, causing the hangover to fall on Monday morning. At this point, you would wake up, realizing you are now alone, causing a second major blow to your face. This feeling is described as the "Monday Morning Hangover"
I'm not going to make it to work, I have a Monday Morning Hangover.