Rainy Days and Mondays

'Mondayitis' or "having a case of the Mondays" is a feeling of weariness and apathy that some workers express when starting the work week on Monday. The phrase entered the pop culture lexicon after its use in the 1999 American comedy film Office Space and it was said that "You get your ass kicked for saying something like that." Many people claim that the "condition" is in fact a diagnosable illness based on the human circadian rhythm being incompatible with a 40-hour work week. However, the medical credibility of the condition is a matter of debate.
Wikipedia

A Tribe Called Quest - Can I Kick It?