How big are we talking? I once had a fuck buddy that was hung like a horse. Nothing really eased the uncomfortableness of it. Eventually I started to enjoy it. I guess you could say it was good pain, but it was never great sex. He always had to take it slow, which was no fun for either of us. And forget anal and blow jobs. I could barely get the head of his cock in my mouth and there was no way it couldn't rub up against my teeth. The affair didn't last long. There was really no point. What good is a fuck buddy if sex isn't enjoyable?