When you are using a messenger application, and you're typing something. You see your friend start to type and out of politeness erase your comment to allow him to continue.
He then does the same when he sees you typing, and you're stuck in a game of Messenger Chicken.
It's best resolved by just typing an lol or smiley face.
I was talkin to Jenny last night but we got held up for like 3 minutes playing Messenger Chicken.