Indicating a true state of shock; unable to produce verbal words, facial expressions and/or further reactions towards another who has provoked this behavior.
While working on a car, these are likely the first words that you will utter when you realize that you have broken an old, rusty bolt that you were trying to remove. When this particular bolt essentially puts the vehicle out of commission until it is resolved and you have, like, two hours to fix the problem, the "fuck" becomes an all-caps "FUCK" and is spoken accordingly.
"Alright, I removed 10 of 12 intake manifold bolts no problem. Now for number 11..."
CRACK!
"Oh fuck..."
Bob: This SOB bolt won't budge!
Joe: Try the breaker bar.
Bob: Alright, let's do it. Hnngh!
CRACK!
Bob: Oh fuck...
Bill: Oh fuck...
John: What happen?
Bill: I just broke one of the cylinder head mounting bolts.
John: What the fuck?! How did you manage...no, fuck it. You better sort it out because I told the customer the car would be ready in two hours.
Bill: But I need longer than...oh FUCK!