The act of screaming at someone without using any vowel sounds, so as to keep the volume of the scream down to a nominal level. Similar to the well known "SHHHH!" but it is actually a word or a group of words. Often used in classroom or library settings, it can also be useful in churches or as a warning that someone unwelcome is approaching.
You are in your cubicle talking with a co-worker about the really weird dude down the hall. As your co-worker is launching into a story about the guy, you see him approaching. You let out a long whisper-shout saying "Stoooopppppp!!!" just loud enough for your co-worker to hear. Fortunately, the whisper-shout has again saved the day, and the weird guy will not be taking you out when he goes on his shooting rampage.