How to Offend a British Person

Memorize this script and repeat it verbatim to a British person:

“You can quit it with that accent anytime you're ready... Seriously, cut it out... Listen, I don't care alright? You can tell whatever story you want but I know it's a fake accent... Just quit it. I know it's a fake accent because I heard you! When you thought I was out of earshot, I listened and you were talking to yourself, alright? So, cut it out... Look, you didn't have an accent when you were talking to yourself. I heard you... Where are you really from anyway, Vernal?”

I have never tried this on a real live British person but I can guarantee that it will totally work.