The "boomy" theory is that when times are good, we get overconfident and spend freely, then retreat into a risk-averse shell when times get tough.

“牛气哄哄型”理论认为，当形势大好时，我们会过于自信，花起钱来大手大脚，而当形势变得艰难时，我们就会缩进厌恶风险的壳里。

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He proved overconfident on the witness stand, misremembering a key piece of evidence.

他在证人席上显得过于自信，记错了一条关键证据。

《柯林斯英汉双解大词典》

Perhaps, too, there may be something about living always in a crowd that encourages loud and overconfident opinion-giving.

或许这也与总是生活在一个提倡说出自负观点的人群中有关。

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Though few of these players were here for the streak, the Knicks were perhaps a bit overconfident heading into the game for a franchise that lost an NBA-record 13 straight postseason games from 2001-12.

WSJ: Celtics stay alive, beat Knicks to force Game 6

Though few of these players were here for the streak, the Knicks were perhaps a bit overconfident leading into the game for a franchise that lost an NBA-record 13 straight postseason games from 2001-12.

NPR: Celtics Stay Alive, Beat Knicks To Force Game 6

Maybe, we're a bit overconfident, but the PlayStation 2 remains incredibly viable -- great contributions to the bottom line and great software for the consumer -- so I think we felt like we could have a little more patience in terms of getting to where we needed to get to.

ENGADGET: & Joystiq interview: Kaz Hirai and Jack Tretton, Presidents, Sony Computer Entertainment, Inc., and America