1. Someone who secretly likes heavy music, but never admits it for fear of ruining his personal image as a well groomed person.
2. The opposite of 1, a metrosexual who doesn't like heavy music, but has friends who love it, and has to pretend he likes it to satisfy his friends. Unfortunetly nice haircuts and mosh pits don't mix.
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.