bum out

From bum (“unpleasant, depressing”).

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bum out (third-person singular simple present bums out, present participle bumming out, simple past and past participle bummed out)

1. (slang, transitive) To cause a person to be depressed or disappointed.
   • 2008 March 5, Rick Weegman, “Cloquet-Esko-Carlton: childhood dreams come true”, in Duluth News Tribune:

     “It bums me out that I can’t play, but I’m glad my brother has the opportunity,” Austin Baker said.

This phrase is mostly used in the passive voice or with the subject it, but unlike the synonymous standalone bum, there exist active-voice constructions such as

 Summer weather really bums me out.