bugger up

verb

1. To break or spoil something, or make it inoperative, useless etc.

   “I've buggered up the sudoku somehow and can't finish it.”

   “Well, he only buggers up one sentence, and that's the first one. He says, 'Shut up, blek.' But from that point on, it was OK because I helped him with it. If I'd been there, I would have told him to say, 'Shut up, black', exactly the same as an American accent.”

2. To injure or harm (someone).