Green’s Dictionary of Slang

1. (orig. US) to come to the end of one’s finances; also attrib.

1938		D. Runyon ‘A Piece of Pie’ in Runyon on Broadway (1954) 675: The character [...] unfortunately taps out on the first proposition and has nothing with which to bet on the second.
1956		I. Fleming Diamonds Are Forever (1958) 72: Drunks [...] were also considered menaces when they tapped out.
1969		‘Iceberg Slim’ Pimp 187: I gotta get my coat pulled before I tap out.
1979		‘Iceberg Slim’ Airtight Willie and Me 131: He pushed his tap-out pile of green into the pot.
1984		W. Murray Tip on a Dead Crab 123: That jerk thinks betting horses is like putting your money in the bank. If horses was boats, he’d have tapped out on the Titanic.
1991		(con. 1920s) O.D. Brooks Legs 155: He’d be next door at the bookmaker’s [...] His absence was a good sign. If he’d tapped out he’d be in the pool room.
2001		Eble Campus Sl. Fall 11: TAP OUT – run out of something, e.g., energy, money: ‘I can’t go to the movies because my checking account is TAPPED OUT.’ // ‘I have got to go to bed; I am TAPPED OUT.’.
2011		E. Beetner ‘Zed’s Dead, Baby’ in Pulp Ink [ebook] He’d tapped out the cash reserves, y’know?

2. to fail, to ‘draw a blank’.

2001

(con. 1964–8) J. Ellroy Cold Six Thousand 131: Pete searched for Betty. He tapped out. That was good [...] Betty got smart and ran.

3. to relieve someone of their last money.

1967		J. Breslin World of Jimmy Breslin (1968) 126: I have to go [...] and tap out on the trumpet player.
1979		‘Iceberg Slim’ Airtight Willie and Me 132: It would be hazardous to his health and winnings to tap-out Starkey.

4. in a fight, to give in, to surrender by indicating with a tap on the ground.

1974		D. Ireland Burn 85: Now you’ve had the dick. Submit. Go on. Tap out. Slap the ground. That’s the finish. You’re history now.
2005		D. Vandenberg Iron Circle 11: Chiao and I would meet, greet, and fight until one of us tapped out, couldn’t get up, or was dead.

5. (US campus) to be exhausted [fig. use of sense 1].

2001

see sense 1.

6. to reach a conclusion.

2002

J. Ellroy ‘Where I Get My Weird Shit’ in Destination: Morgue! (2004) 34: The crisis tapped out. The arometer lied.

7. (US drugs) of a dealer, or individual, to reach the end of one’s drug supply.

2002

Simon & Burns ‘Cleaning Up’ Wire ser. 1 ep. 12 [TV script] We gonna tap out by noon.

8. (US) to die.

2017

D. Winslow The Force [ebook] ‘Harry tapped out in the saddle and we want to spare the widow and the kids the embarrassment’.