A person (usually a guy), that is genuinely nice and
mild-mannered, but is prone to bouts of assholery, jackassery and basic insensitivity.
Mostly, Simple Dicks are unaware of their apparent faux pas' and think nothing of them. They don't think twice about other's feelings and give the impression of either feigning ignorance or being simple.
Simple Dicks are not purposely that way. Usually they are the friend that says the wrong thing all the time. They have "Tsundere-like" qualities, but are more inconsiderate and insensitive.
Carmine: "Jesus man! Your such an ass. Why are you always such a simple dick? I know Janet can be a bit much, but why'd you have to say what you did? I mean, she just broke up with her boyfriend for shit's sake."
Lucian: "Oh well man. She shouldn't have broken up with her boyfriend. That shit isn't my fault. I could care less."
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.