Green’s Dictionary of Slang

1. (US) to increase, e.g. money or stocks of drugs; thus as n. an increase, a profit.

1975		C. Trilling in New Yorker 17 Mar. n.p.: [of profiteering from house purchase and sale] he difference between an established family and a new family sometimes seems to be that the established family pulled off some successful land-flipping in the thirties instead of the fifties.
2000		]W. Shaw Westsiders 264: Flipping it: the entrepreneurial dream of the perfect hustle in which a buck makes ten, a gram of cocaine makes a kilo.
2008		Young Jeezy ‘My President’ 🎵 Had to hit the streets try to flip some keys / So a nigga wont go broke.
2014		Young Jeezy ‘Me OK’ 🎵 Break ’em down into zips, that’s a hell of a flip.
2017		hubpages.com ‘Roadman Slang 4 Jun. 🌐 Flipping - selling/dealing, anything from CDs to narcotics.

2. (US) to renovate.

2019

S.M. Jones Lives Laid Away [ebook] ‘I flip houses’.