Green’s Dictionary of Slang

1. (US) a deliberate loss.

1964		E. Wilson Earl Wilson’s New York 4: ‘It was a dump. I lost on purpose, because she said she’d give me a date if I let her win [i.e. an eating contest].
1969		L. Schecter Jocks 3: [T]his book is about [. . . .] the dump, the fix, the thrown game, the shaved points, the cross and double cross.

2. (US prison) a rejection of parole.

2002

(con. 1998–2000) J. Lerner You Got Nothing Coming 244: Two-Tears recently spun the parole Wheel of Misfortune and came up with the worst-case scenario — a ‘dump until expiration of sentence’.