"Oh Shit" moment
The point in time when you realize
that what you originally thought was a good idea, was in
actuality really stupid.
OR
The point when you realize you forgot something
crucial, but too late to do anything about it.
After Bob
pulled the ripcord on his
parachute, but it didn't open, he realized he didn't even pack a parachute for his dive.
His "Oh Shit" moment went something like this:
"Shit."
*
thud*