you're fucking weird. so, when you have sex, you don't leak any penis fluids at all? or do you throw the towel out because otherwise you're gonna mingle the bodily fluids with your laundry, which you seem to have forgotten contains other bodily fluids. and what about if you have a little precum before you get your pants off? do you throw your undies away when that happens?
The rule is: Anything that comes from my penis in the company of a female is OK and not considered dirty. Penis juice is great and clean when it is mixed with vaginal juices. Anything produced while alone is dirty and shameful. Like urine, shit, and mastubatory emissions.
i wash my sheets every 2 weeks so this isnt an issue for me (more often after a particularly messy sexual encounter). i've never jerked off on a toilet, its not really conducive to getting me hard when im on a toilet. i get off in bed or in the shower. i wouldnt piss in a shower though cause no matter how much water you run, that urine smell lingers.