Get Shit Done Day

A day after a really terrible event in which you suddenly have the motivation to do way more than you would normally.

A: I cleaned my whole house after Katie broke up with me.
B: But you never clean anything.
A: Yeah, I was just having a Get Shit Done Day.

get in some gangster shit

To go out and fight someone
Beef

Man 1: fuck u
Man 2: u want to get in some gangster shit?