When you pop your collar, you reach up to the shoulder of the correspoding arm or across the chest to the opposite shoulder, and, using your index finger and your thumb, you pull up on the shirt and let it "pop" down, hence the phrase. It is perfectly
acceptable to pop your collar whenever you have
accomplished a great, admirable feat, such as busting a sweet dance move, pwning the entire opposing team by yourself, or to establish your
extremely high playa factor.
Derek,
obviously outmatched, kills all 4 of his
enemies alone. Derek pops collar, and TJ holla's "Thats right, pop your collar
home boy!"