Sneak dissing is to make fun of, diss, or roast someone else without telling them, normally in a whisper.
For example, if you are whispering to your friend about someone else that is
right there and he doesn't hear it, it's sneak dissing. However, if you say it loud enough but he is too busy in
something else, it isn't considered sneak dissing. Commonly referred to as
snake dissing by wiggas.