A text message that is sent to someone under the assumption that you know that they're going to text you. Commonly used with tech-deficient family members who take forever to answer text messages.
I sent a Preemptive Text to my mother to inform her that i was driving home, because I knew she was gonna ask where i was.
n. A text sent to a friend whom you are about to visit, alerting them prior to your arrival.
Phil - "Hey guys, we're about to go to Joe's house."
Zeek - "Does Joe know this, or are we just going to show up?"
Phil - "Yeah he knows. I sent him a preemptive text."
Jason - "Wanna' go to Steve's?"
Ralph - "Sure, but let him know or he won't answer the door."
Jason - "One preemptive text, coming up!"