It's absolutely time to jump in the bath and get cleaned up.
Below are steamy positions perfect for the bathroom.
It's a toilet, but it's also the perfect height to sit on his lap and ride him. Close the toilet cover, throw a towel over it and hop aboard. Make sure you're facing him—the other way feels way too close to regular old peeing. Have him use two fingers on either side of clit and rub as you ride and you will no longer care that you're doing it on a toilet.
If sex must happen immediately, just bend over the sink so he can enter from behind in a standing doggie. Fill your hand with lube and rub your clit, with an occasional circuit to stroke his balls and penis as he moves inside you.
Try a standing position with your foot propped up on the sink, sticking your butt back a bit for a better angle. He reaches around with a vibrator while you both admire your mutual hotness in the mirror.