|1.||ah fuck, I can't believe you've done this.|
A statement of frustration said when one is about to say something and is interrupted abruptly; usually with a punch to the face.
Note: It has to be said in a non-enthusiastic, brittish, calm and polite manner, if you will.
Some guy: "Hello everyone, i'm here today to talk about... *PUNCHED IN THE FACE*
Same guy: "Ah fuck, I can't believe you've done this."