I know a lot of people have heard of this, but here's to the people who haven't.
I do this on times when I'm really horny, but don't want to work a lot.
Turn on the water in the bathtub to a warm temperature, but not too warm. You can adjust it (I do with my feet) while you do this. Lay down on your back with your legs open, with the water running over your pussy. Position yourself so the water is aimed at your clit and work your tits with your hand. If you want to, you can put a bath pillow (the blow-up ones) under your backside to prop you up a little more. As you get further and further along, you can turn up the heat a little more, which makes it feel great. It gives you an AMAZING O.
A tiny trickle of cold water also feels great afterwards.
Try it, it's amazing.