The one day of the week where you can be dirty! lots of people do "dirty" things so why not a day named after it? Tuesday is said to be the dirtiest day of the week naturaly. The day where you can have sex of any type woth any person.
boy: Hey, what are you doing today?
other boy: Its Dirtytuesday so im doing my girl!
boy: Man, i love Dirtytuesday!!
Of the seven days of the week, Tuesday, otherwise known as Dirtytuesday or dt, is the day you can do anything dirty. If you're planning on hooking up with someone, do it on a Tuesday!!
Guy1: I just hooked up with this random girl!!
Guy1: Why not?! It's Dirtytuesday!