How do you communicate with your teammate without a microphone? Is there a kind of body language that players use?
There isn't any way to do that. However, I do know of clans which practice regularly and hence know each other's moves and styles. They often set up signals such as movement patterns and seemingly random bursts of gun fire, to give each other quick information (for those who don't have a mic). I've seen this before and I was pretty amazed. But the short answer is, other than morse code and an RPD, you don't have much in the way of means of communication without a mic on a console.
I've had to resort to a cell phone conference call when a teammate's mic broke. Using speakerphone or a headset, it's basically equivalent to a mic, especially if you have an easily accessible mute button. Most cell phone plans now a days offer unlimited talk after a certain time or mobile to mobile to it's not a big deal minute wise.
I use Sit Rep Pro a lot and can therefore can see explosives through walls. When there is a teammate next to me that I don't know, I typically just start shooting at the wall next to the doorway and most of the time they understand and don't blow themselves up. That's much easier than trying to read their gamertag and yell out a distinctive enough landmark so they'll understand that you're talking to them.