I'm a Catholic and have done extensive study into the disputations of our medieval theologians - while they might have argued about whether an angel was a separate substance and therefore indivisible by genus into species, they never tackled such topics as praying while on the thunderbox.
Mordechai Torczyner's WebShas - Index to the Talmud: Mealtime Issues: Bathroom Issues (You can also type 'slave' into their search engine to get an index of the many places in the Talmud which regulate master-slave relations.)
Sure enough, there is plenty to legislate about bathroom behavior, including a prohibition on wiping oneself an even number of times (the practice is evocative of magic).
On the other hand, a search in Google for 'prayer bathroom' reveals several Christian sites which recommend taping prayers to the bathroom mirror for regular recitation, or going into a bathroom for privacy to pray. I'm not sure which is weirder....