There was dodo on the floor?

so I woke up this morning to find human crap on the bathroom floor and hallway(ewww I probably stepped on it when I used the bathroom last night), it belongs to my sis. Only me and her use that bathroom. My question is how the hell did it get on the floor, and why didnt she clean it up. When I told my mom about it she didnt do anything. I flipping had a fit and went off on both of them. Was I wrong what would you guys have done in that situation.