There are many synonyms for the phrase "going bad" which can be used in everyday conversation to avoid repetitiveness. Some of these synonyms include deteriorating, spoiling, rotting, decaying, perishing, degenerating, going off, souring, curdling, and turning rancid. Each of these synonyms describes a different stage of the process where food, drink, or some other substance slowly begins to spoil or decay. It's always good to have a variety of words to use in conversation to make it more interesting and engaging. Whether you're talking about food or something else, using the right synonym can add depth and nuance to your meaning.