go bad

Wiktionary

1. v. Of foods and commodities, to spoil, rot, or otherwise become unusable due to age or storage conditions.
2. v. Of a person or entity, to cease to be reputable and instead become delinquent, criminal, or poorly behaved.
3. v. Of a geographic area, to become unsafe.

WordNet 3.0

1. v. become unfit for consumption or use
2. v. stop operating or functioning