I'm pretty sure its in this one. It's where Chandler wants the chair he was sitting in, and Ross is mad because neither Chandler nor Joey is getting dress. Joey takes the cushions "the essence", so Chandler hides Joeys underwear. Then, Joey gets mad, says "I'll do the opposite to you" And puts on "every single piece of clothing he owns" He then proceeds to say "Maybe if I wasn't going, COMMANDO!" Then he does the lunges. If he wore all of Chandlers clothes, he would have worn all his boxers. Thus, not commando.