The ability to text message your friends with your thumbs just as fast as you would be able to send an instant message on the computer keyboard ... or dial their number and talk to them.
My dadsimply is not textidextrous. He can only write with one thumb ... and he's sloooooooow.
An incident or accident when you collide with someone on the street who is too busy texting to look where they are going.
In the street when you are caught in the path of an oncoming Text Messager, you narrowly escape a Textident by jumping out of the way. Also screaming "Textident!" in their face at the last moment may save you, but 2 out of 3 texters are also wearing headphones and you will probably get mowed down anyway.