term used when members of military service (usually males) see a very attractive woman whether the female is miltary or civilian, and slightly refers to the military term of standing at attention-in this case for the gorgeous lady.
Male 1: " Wow Poh-rade rest!"
Male 2: "Agreed"
Female : "Did you see the girl driving that hummer?
Male : "Was she parade rest material?"
Female : "Phuck yea!"