"Even worse, these public latrines were notorious for terrifying customers when flames exploded from their seat openings. These were caused by gas explosions of hydrogen sulphide (H2S) and methane (CH4) that were rank as well as frightening. Customers also had to worry about rats and other small vermin threatening to bite their bottoms. And then there was the perceived threat of demons that the Romans believed inhabited these black holes leading to the mysterious underbelly of the city."
Sounds like it was far better if you could hold it until you got home to your own private toilet, which was probably in the kitchen right next to where your slaves were preparing your next meal[2].
[1] https://phys.org/news/2015-11-toilets-sewers-ancient-roman-s...
[2] https://scx2.b-cdn.net/gfx/news/hires/2015/564dcb76b9497.jpe...