This term originated from a fight between two highschool students in University of Colorado. One of the high school students did a clothes line on the other but the other student caught his hand and twisted it untill it popped 2 times. The student then went to the health room, and the nurse heard his arm crackling likerice crispes, the term then got popularized and used in underground fights.
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.