Rarsday (n.) The day of the week that lies between Wednesday and Friday. In scheduling abbreviations, the days of the week are often indicated as "M T W R F." The day between Wednesday and Friday, therefore, is often referred to as Rarsday.
Referring to this day as Rarsday instead of it's traditional moniker, Thursday, generally indicates drinking, tomfoolery, shenanigans, merriment, and other bits of debauchery
I just woke up next to three hookers in a pool of my own vomit with coke scattered all over myself and a new dick piercing that I have no clue how I got. That was one hell of a Rarsday.