How do you do a battle cry in Metal Gear Solid peace walker

First, press start (or select, if you put it with the select button) and choose Co-ops comms. Then, well, you choose! Battle crys are words that can make people happy or sad. For example: say you're with your buddy and he's falling behind. Well you can either encourage him and make him go faster, or do the opposite. It's also called Kotodama (if you don't know what the bolded word means, try looking it up on Google).