This awkward exclimation usually only happens around small children or parents. If you are trying to be polite, or trying not to be smacked upon the head, this expression should come up often in certain situations.
When something alarming happens, you can't help but to say "oh shit!" usually mid sentance you realize it's "innapropriate" so you add -oot to the end, as if anyone believes you actually were going to say "oh shoot".
"oh shhhh...oot "
"Who are you trying to fool? Everyone knows you just said shit."