50 hours sounds like that’s average for how long it takes for food items to be fully digested and completely excreted from the body under normal circumstances, but not necessarily an average minimum amount of time for how long it takes food to start exiting the body in feces.
Those are very different data points, especially in the context of a discussion about spicy foods.
Spicy hot foods are typically spicy because of a chemical called capsaicin, which is an irritant in mammals. In high enough amounts and/or in sensitive people, capsaicin can irritate the lining of the digestive system and that irritation can have a laxative-like effect to varying degrees. In response to irritation, digestive motility / speed will increase, and the general trend is that the quicker something moves through the digestive tract, the less completely it is processed and digested.
Basically, if someone eats too much spicy food for their tolerance level, it is fairly typical for that to move through the digestive system more quickly than average AND the feces will contain proportionally more capsaicin. So, bowel movements less than 24 - 50 hours after eating the spicy food and a burning sensation associated with the act due to undigested capsaicin actually does make sense.
