The act of sending a Text message to someone and not receiving a reply immediately, whereupon the recipient replies, and you have no idea what they are talking about
LISA: Sure! where did you have in mind?
JON: What? What are you talking about?
LISA: You asked if I wanted to go out tonight.
JON: Oh! sorry, I had Textheimers.
A condition in which you text a friend and unknowingly forget a couple words in the messages repeatedly because you were sitting/standing next to a beautiful woman, thought you typed the words already, were listening to dubstep, or are a titanic idiot.
Texter 1: I lied earlier, I listened to a mess phat dubstep! Then I went store and grabbed a shit-ton of chips! Nomnom :&
Texter 2: ??? That's the fourteen message in a row where you have forgotten some words cause these messages barely make sense.
Texter 1: I haven't been forgetting words. (Checks through sent messages)
Texter 1: Oh shit. I think have Textinheimer's!