Making a mess while getting clean

My boys are creative. They can always find new inventive ways to make a mess. Our bathroom is sort of split into two sections. While the boys were in the tub I was in the other part of the bathroom so I could hear the other person on the phone. I could hear the boys having lots of fun, but they always have fun in the tub. No one was crying in pain so I let them be. Then it got to a point where that laughter turned into a laughter that meant, "the boys are having way too much fun and are probably getting into trouble." I peeked into the tub and sure enough, the boys were in trouble. They were in the process of dumping half of their shampoo into the tub. They had created a huge bubbly mess. They that it was a lot of fun to lay down and slide on the slippery mess. I wrapped up my phone call, just as I was getting another. My mom asked if I was busy. "Oh no, it's just that the boys dumped a bunch of shampoo in the tub and have covered Cordelia in bubbles." I probably wouldn't have gotten so mad, but the floor had a bunch of water on it. Nothing irritates me more. The boys got out of the tub and there was not an inch of their body that wasn't covered in bubbles. After they had their pajamas on they went to bed without a story as punishment. I actually thought the whole scene was quite amusing, but I couldn't let them know that. I don't want this to be a reoccurring thing.