To not wash after taking a crap
I live by myself, so I frankly often see no reason to wash my hands after I take a dump. Sometimes, I'll even cook and all, without having bothered to wash up afterwards. Honestly, I usually only wash if I get some on my hands. When other people are around, I always wash though as many people would likely get quite grossed out by this.
It's odd because I used to be a total germophobe about stuff like this. I've kind of grown out of that though as I've gotten older and honestly don't necessarily even bother washing. Especially since some family members have been the same way about it and never experienced any problems as a result.
While I do sometimes wash after taking a dump, I've never washed my hands after taking a leak. However, apparently other people do, which I wasn't even aware of until I was in high school. My gym teacher noticed I didn't wash and said something to the effect of, "that's gross, wash your hands". I was honestly a little perplexed as I never even heard of anyone washing after taking a leak.