Use a comma to separate a direct address (even a rude one) from the rest of the sentence. (Yes, I know there’s usually no comma when this expression appears online. What’s your point?)
Also, the titles of computer games should be capitalized, and Mario Kart is not hyphenated.
“Bitch, please, you don’t think I can beat you at Mario Kart?”
(It could be argued that the title of a computer game ought to be italicized. The game is, after all, a long-form digital publication of a sort. However, this is not mentioned one way or another in CMS, so I’m not entirely certain, and of course the internet is useless because the internet, as a whole, doesn’t believe in italics in any usage.)