When something bad has happened or is about to happen, you shout OH NOOOOESSS as a replacement to the dull, tired "oh no". Extra o's and e's can be added for extra emphasis.
You remember lemmings? When you nuke a lemming he says "oh no" and explodes. If you truly mess up a level beyond repair and the only thing you can do is lose, you mass nuke your lemmings. They all say "oh no".