Blue T-Days are the two days in the week that start with "T" as in Tuesday and Thursday, those are the days you wear blue underwear or panties.
Girl:"What is today???"
Guy:"Hold on let me check." *glances down at their underwear real quick* "Tuesday or Thursday."
Girl:"Blue T-Days?"
Guy:"Yep."
Girl:"Oh."
Guy:"Hold on let me check." *glances down at their underwear real quick* "Tuesday or Thursday."
Girl:"Blue T-Days?"
Guy:"Yep."
Girl:"Oh."
by Dalyena October 26, 2015
Get the Blue T-Daysmug. 
by Yo moms a hoe May 15, 2019
Get the T u dmug. Your average everyday local alcoholic in small town iowa that enjoys playing guitar chugging the fuck outta beer and staying outta jail.
by Fat-T Onawa Iowa 712 December 19, 2021
Get the Fat-Tmug. 
