Your Hard Cock

You've gone to visit your mate but he's passed out in bed, so instead, you find his sister bent over the sofa trying to look for her phone. You can see right up her dress to her panties and it's making your cock twitch. She spots you checking her out and sees your hard cock through your trousers, but you've known each other since you were kids! Is this not a bit weird? But before you know it, she's flashing you her pussy while you wank your cock!