age like milk

Referring to milk’s tendency to go bad quickly.

age like milk (third-person singular simple present ages like milk, present participle aging like milk or ageing like milk, simple past and past participle aged like milk)

1. (simile) To age very badly; to look bad in hindsight, or after time has passed.

   Synonym: age like vinegar

   Antonym: age like a fine wine

   While rewatching this movie after twenty years, I realized that it had aged like milk.