Wiktionary
bum out
vb. (context slang transitive English) To cause a person to be depressed or disappointed.
Usage examples of "bum out".
That torch will bum out soon, he thought, and we are all alone, without food or friends or fire.
They bum out or fail in any of a hundred ways--and the cases you’.
You've been trying to make a bum out of me ever since you've known me, but you're not going to do it.
They bum out or fail in any of a hundred ways--and the cases youre talking about are robots who were expected to deal with very distant, abstract sorts of situations.