i can't believe you've done this
What you say when someone interrupts you right before you’re about to say something cool, and then they punch you in the face like it’s a tradition.
"I can't believe you've done this" after being interrupted mid-sentence by a punch.
"I can't believe you've done this" when someone interrupts their big speech with a surprise punch.
"I can't believe you've done this" after someone just ruined their moment with a punch to the face.