I have had dcks poop in their pants/underwear before and I 'rinse ' it in the toilet without touching anymore than I possible have to. I pinch the waist band of undies (or whatever part that is not soiled) and flush a couple times while dunking and whisping the undies around the toilet bowl as it flushes. I find this does an 'ok' job without me ringing anything or getting my sink dirty. I then bounce it over the toilet to get some water out, double or triple bag it and leave it for parents to take home. At least the majority of the poop is in the toilet that was in the underwear and they are still soaked so nothing should stain on clothing until it dries on.