Prefix used before a person's name to create a new name applied to a different person who looks similar. Example: Ed: Hey, look over there, it's not-Ted. Ted: Haha, I should go talk to him. It would probably look funny, the two of us. People would think we were twins or something.
NOT-
Meaning of NOT- in English
Slang English vocab. Английский сленговый словарь. 2012