Ha, this one will probably get some interesting responses. But urine is sterile, so unless you keep your unmentionables the same way you keep a landfill, there is no need to wash your hands. Going numero dos is another story. The natural bacteria growing in the doo can be bad for you, so you definitely need to wash after that. One's a play ground and the other is a sewage treatment plant, i'll leave it at that.
Ha, why is this on a shooting forum again?
It is true that it is sterile, but it is also a great media for bacterial growth, so you want to wash it off before stuff starts growing.