Dic: cash in: some of its meanings

cash (one's chips) in:

• 1. I guess I'll cash my chips in and go home.
• 1. Well, it's time to cash in my chips and go home.
• 1. I'm really tired. I'm going to cash in.
• 2. Someone: There's a funeral procession.
  Someone else: Who cashed his chips in?
• 2. Poor Fred cashed in his chips last week.

1. Fig. (1) to quit [anything], as if one were cashing in gaming tokens | (2) to leave or go to bed.

2. [also Cash one's checks in Euph.] to die; to finish the "game of life."

... McGraw-Hill Dictionary of American Idioms and Phrasal Verbs,
http://idioms.thefreedictionary.com/cash+in

cf. PHRASAL VERB | If you say that someone cashes in on a situation, you are criticizing them for using it to gain an advantage, often in an unfair or dishonest way.

• Residents said local gang leaders had cashed in on the violence to seize valuable land.

... Cobuild