Don't Tell Me BlackBerry Messenger
This term is used by BlackBerry users when someone asks then for their PIN and they do not want to give it. The term can also be used in a sarcastic/comedic way (see example 1b below).
The term rose to prominence through the backlash to instant messaging in favor of more traditional terms of communication.
a) Girl: Hey Charlie what's the deal? You never send your PIN?
Charlie: Are you for real? Don't Tell Me BBM/DTMBBM!
b) Girl sees a hot guy: Mmm, he can tell me BBM any day of the week.
c) Guy sees unattractive girl: Jeez, DTMBBM if you know what I mean.