DT = Dicktease. A girl who usually talks about doing dirty stuff with you, but ends up never doing it. This is usually done via Text Messages or Online, so they can't be caught lying.
Mandy: Hey ;)
Chris: Hey ;)
Mandy: That party tonight, would you want to hook up? ;)
Chris: Damn rights!
Mandy: Actually, I don't want to anymore. Sorry
Chris: Haha, you're such a DT!