In cities where there are bans on texting while driving, the textratary is the title given to any person, usually whomever is sitting in the passenger seat of the car, that will type out your message for you so that you can have a conversation with your friends. The only down side to this is that the textratary could end up talking to all of your friends while your driving.
Just like a regular secratary only one you have sex with instead of your spouse or current significant other. So, it fitting in the terms of s"extra"tary.
The whole office was buzzing with the latest news:
Morgyn: "Did you hear about, Jim?"
Keegan: "No, what happened?"
Morgyn: "Jim's wife came to bring him lunch and walked into his office to find him having a nooner with his sextratary right on his desk."
Keegan: "Sucks to be him."