涨知识：13个让你看不懂的英文习语的起源

"Bob's your uncle" is a British exclamation that means you've achieved something simply. Although its origin is debated, many researchers believe it derives from the nepotism of Lord Salisbury.
“鲍勃是你叔叔”是一句英国习语，意为轻而易举地做成某事。尽管关于此习语的起源众说纷纭，但很多研究者认为它来源于索尔兹伯里勋爵的裙带关系。

In 1886, Prime Minister Robert Gascoyne-Cecil (Lord Salisbury) surprisingly made Arthur Balfour Chief Secretary of Ireland; Balfour was ‘Bob’s’ favorite nephew.
在1886年，英国首相•加斯科•塞西尔（索尔兹伯里勋爵）任命亚瑟•贝尔福为爱尔兰布政司；而贝尔福是鲍勃最喜爱的侄子。

There are a few other phrase origin possibilities, but this is the likeliest of the bunch.
也许这句话还有其它来源，但这种解释的可能性最大。