Oh Shit Moment
1. The point of realization that you forgot to do something important.
2. The point in time of a discovery that you forgot a step in assembly or development process when you realize you forgot an earlier step.
3. A moment of surprise occurring when some new information is discovered that provides a negative or detrimental result in an otherwise wonderful event.
Ricky had still another OSM when he discovered the hole in the condom he used last night.