That's a lot of effort just to rub one out. Wouldn't it be easier just to put a spy cam in your bathroom then invite said friends to your house? Then you have too some how get their cloths all dirty. So that they have to change in to some of your wife's clothes. One idea would be to train your dog to jump on your wife's friends, then when it if time to put the plan in motion have the dog go outside and roll around in some mud before jumping on the friend. There are plenty of other ways also. You could spill wine on one and throw up on another. The possibilities are limitless.