A dark horse bobbing up 爆冷门儿
【注音】bào lěng ménr
【解释】一向冷清的角落突然热闹起来，不被人看好的东西突然成为关注的焦点。
When a deserted corner witness a scene of bustle and excitement, you can say its cold door is exploded. Therefor, when something that is believed to have no good prospect became an unexpected winner or the center of attention, you can use this expression.
       
【例子】
例1：AC米兰队被北京国安队打平，算是爆了一个不小的冷门儿。
Ex1.：The AC Milan ended up with a tie with Beijing Guoan, which really is an unexpected result.

例2：世界杯足球赛这两天连着爆冷门儿。
Ex2.：There were dark horses bobing up one after another in the past few days’World Cup.


背黑锅
Be unjustly blamed
【注音】bèi hēi guō
【解释】代人受过或者被人冤枉，那感觉不是很像“背上了黑锅”吗？
Don’t you think this expression vividly describe the feeling of being made a scapegoat or unjustly blamed?
    
【例子】
例1：
A：这个办公室里老有人说丢了钱，是怎么回事嘛？
B：这事儿得查一查，不然的话，好像一屋子贼似的。
A：是呀，我们这屋子的人都背着黑锅呢。
Ex1.：
A：People keeps on complaining about losing money in this office. What’s all this about?
B：We’ve got to investigate into this matter, otherwise it seems our office is full of thieves.
A：Yeah, I agree. We’ve all acting as scapegoats for the thief now.

例2：儿子名声不好，老子也为他背黑锅。
Ex2.：If the son has bad reputation, the father will also be unjustly blamed.