A popular phrase amongst chavs and their ilk. A less formal way of saying "good sir, I believe you have wronged me, and I hereby challenge you to a match of strength to determine which one of us is the superior fighter."
Chav 2: What the fuck you doin', blad! You fuckin' startin', like?!
Chav 1: C'mon then bruv, I'll shank you 'ardcore like!