When a person IM's or messages the wrong person.
mostly if the person sending the message sends something personal
Guy1 to Guy2 : yeah so what did you two do last night???
Guy2 to Girlfriend (miss-tell) : well me and her went ass to mouth and then i just strait fucked her vag
Girlfriend to Guy2 : WTF YOU ASSHOLE!!!! WHO WERE U TELLING?!?!?!?
Guy1 to Guy2 : sooooo???
Guy2 to Guy1 : .......................
^^^^^ Epic Miss Tell
When you accidentally write something and send it to the wrong person in a written communication. Most commonly with Instant Messaging, but also in texting and emailing.
Roo: "Dood Shax's mom is hawt."
Shax: "I's gonna stab you's inda jaw!"
Roo: "Woops misstell!"