go bad

from Wiktionary, Creative Commons Attribution/Share-Alike License.

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

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb become unfit for consumption or use
• verb stop operating or functioning