A day generally created for the purpose of making people wish they were someone else. The day you realize you have 4 days of work ahead of you and that they won't be going by fast at all. Symptoms generally include feeling like crap, wishing you were dead, or not showing up for work in general.
Something said by obnoxiously cheerfull bastards when someone is feeling tired and/or cranky. Mondays tend to be a horrible day since it's the first day of the working week. Made famous by the movie Office Space.
Peter Gibbons: Let me ask you something. When you come in on Monday, and you're not feelin' real well, does anyone ever say to you, "Sounds like someone has a case of the Mondays"?
Lawrence: No. No, man. Shit, no, man. I believe you'd get your ass kicked sayin' something like that, man.
A disease that affects every human being in the world on a Monday. Where you don't want to do anything but you have to whether it be work or school. Symptoms include depression, anxiety, and not wanting to get off your lazy ass.