Well - as I tend to think everyone actually knows what I am talking about, I had better make it perfectly clear about the treatment and what you actually do with the Bleach.
You DO NOT wash your Willy in the Bleach! It stings bad enough without resorting to anything like, use Bleach, A Brillo pad and plenty of elbow grease :-)
The reason you use Bleach for 6 hours after the treatment is that you are disposing of a Bio Hazard because the BCG is a live vaccine of TB type stuff (Hope that was technical enough for you?). After you have "voided" or had a pee. You must sit to stop splashing BTW - a sure fire way to make sure that the man in your house keeps the lid down :-). You put the bleach into and around the pan and leave for 15 minutes before flushing. The Hospital give you bleach tablets to do this.
So - now you know - please keep the questions coming in - it made me laugh when I read it the first time, then it made my eyes water at the thought of it