sell down the river

sell someone down the river

to do something which harms or disappoints someone who trusted you, in order to get an advantage for yourself. A lot of people feel they have been sold down the river by a government who have failed to keep their pre-election promises.

See also: down, sell

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sell someone down the river

to do something that hurts someone who trusted you. Workers complained that their leaders sold them down the river in the latest contract negotiations.

sell out someone/something

See also: down, sell