Eventually it'll wear out and fall off on its own. In the meantime underwear can be washed in-place.
what if your not wearing underwear?
Just once, or always? As long as nobody else ever knows of this I don't think it'd be that big a problem.
Never Nude?
Its called would you rather ... forever so obviously its forever.
Where should this comment appear?
This pairing only
Whenever "Wash your clothes in the toilet bowl" appears
Whenever "Never take off the underwear that you are currently wearing ..." appears