I won't pretend to understand it, but I'm told that strictly observant Muslims have some pretty regimented toilet protocols. For example, they use stones, not paper, must wipe a certain direction, must use one hand but not the other, and must cleanse with water. Something like that. Maybe different sects within the faith have different rules. I'm no expert, maybe one of our Islam experts will tell me I'm all wrong, but all I remember is hearing that he no longer uses toilet paper.
Yes, this may sound strange, outlandish, absurd and completely over-the-top, but the consequence of some interpretations of Islam is that you should not use toilet paper. The reason is that there is apparently a
hadith (which I have yet to read) in which Muhammad recommends how to wipe your behind. This may sound obscene, but in an Islamic context, it makes a lot of sense, because one of the most important duties of a Muslim is to remain ritually clean (
wudu'). In Islam, the doctrine is 'better safe than sorry', so there are guidelines for
wudu' based on virtually all of life's situations, and much of it has to do with toilet situations (there are even more and extremely explicit regulations on sex). Now, the rules of Islam were written long before such a thing as toilet paper was invented, and Muhammad recommended using stones to wipe your behind to get the greatest degree of cleanliness after excretion. Most Muslims nowadays use toilet paper under the rationale (if they even think about it), that Muhammad would have recommended toilet paper, had it existed in his time. But some fundamentalist interpretations of Islam support only a direct and literal following of the Qur'an and the
hadiths, meaning that if God or the Prophet didn't explicitly say it, it's not allowed. By that consequence, toilet paper is
haram (ritually banned), and you must use stones because the Prophet said so. Of course, and I cannot stress this enough, only followers of certain fundamentalist movements will even think about checking what the Prophet has to say about your bowel movements and how to deal with them.