When Johnagold catches a whiff of Flight Risk in the thread Lantern Light, just after the foal has crawled through a toilet and its sewage pipes to get to the Everfree Forest. The narrator (JM 95) breaks the fourth wall and advises the people of the site to not use public bathrooms.
"It smelled just like one of those awful public toilets at Stall-Mart. The narrator recommends that you try to avoid using those, by the way. They're covered in unspeakable diseases."