This is both a way to cum and clean out your self. What you will need is a bowl of about 3 or 4 ice cubes (depending on what you can fit), a towel, lubricant, and something to stimulate your clit or something to penetrate you (dildo, etc.).
Anyway, what you do is place a towel down where you are going to sit. Then you take some lube and apply it on and/or in your ass. Then you take an ice cube. (Make sure it's not sharp. If it is, suck on it for a moment). Push the ice cube into your ass. It will make it feel so good like your ass is full and cold. Then, if you wish, right away you can add more ice cubes. If not, start stimulating your clit or using a dildo. When that ice cube melts replace it with another. If you get off before your ice cubes melt, you can get the water out by the same method of going to the bathroom. This will also clean out a lot of your anal tract (good if you like anal sex). And clean up is easy, towel in the hamper, lube away, and bowl in dishwasher. I hope you enjoy this as much as I do! ;)