Look, there's a reason why Verizon isn't selling walkie-talkies. If you want to use your cell phone as one, please go to the toy aisle in Wal-Mart and buy a pair. Cell phones have those nice speakers that are built for your ear and pretty good microphones that will pick up what you say. You can hold the phone up to your head and, I promise, the person on the other end of the line will be able to hear you.
Trust me, if they could see you talking to them would probably think you're an asshole, too.