The worst day of the year, scientifically worse than any other Monday. Whack Monday is the first full Monday back to work after Christmas/NYE.
by Angry Albanian January 7, 2019

When you’re doing 69 and she bites your cock so you make a goose noise in her vagina. Only on monday’s
by eddy051705 January 23, 2022

When a girl wakes up on Monday feeling down (because it's Monday) and decides she looks ugly (when she looks fine) so wears slightly too much makeup in an effort to feel better. The excess makeup doesn't necessarily make her look bad, but it is just more noticeable.
by LaBruhn Jaymes July 23, 2015

by nina541 November 30, 2010

A friday which feels exactly like a monday. Monday-Fridays tend to be horrible in the way that you are extremely tired, with no sense of pending freedom.
by DancingWhale December 1, 2010

The Monday immediately following a weekend during which an unusually high number of co-workers or fellow pupils get haircuts and come into work or school with notably different hairdos.
Matt: Yo look at Rob's haircut!
Chris: Dude FIVE people in my homeroom got haircuts over the weekend.
Matt: I guess it's Haircut Monday!
Chris: Dude FIVE people in my homeroom got haircuts over the weekend.
Matt: I guess it's Haircut Monday!
by feltonandkundla October 20, 2009

The day after Sunday Funday, when you are hungover at work and feel dumb for drinking so much the day before.
by Rynomite13 August 16, 2010
