So many of my younger days were spent in Las Vegas and I remember reading about the very real problem of a 5000 room hotel having synchronized flushing. They could run low on water pressure and as a result tanks would not refill, which meant a toilet bowl with no water and sewer smells could come back into the room.

As it turned out one of the big bad guys was their porno video channel. It ran basically continuous movies from some flat fee, and whenever a movie ended a large number of flushes would happen, enough to cause a few dry toilets while waiting for pressure to come back up. Their "fix" was a hack to offset the feeds to various floors to move the breaks up.