"Bob's your uncle" is a phrase heard mostly in Britain, Ireland, and other Commonwealth countries. It has its roots in a situation in 1887 where British Prime Minister Robert Cecil (a.k.a. Lord Salisbury) needed to appoint a new Chief Secretary for Ireland, which was a very important and sensitive position. He appointed a man named Arthur Balfour for the position. The problem was that most of the time, Mr. Balfour knew Lord Salisbury as "Uncle Bob".
This was a blatant case of nepotism, and people were very upset about it.
For a while, "Bob's your Uncle" became a popular sarcastic phrase to use about any situation where the result was preordained by favoritism. Over time, the situation was forgotten about, and today the phrase has a meaning more like, "There you have it", or "You're all set." It's lost a good deal of its edge.
For instance, if I were teaching you how to make your bed, I might say, "Put on the sheets, add the comforter on top of them, put the pillows at the head of the bed, and Bob's your Uncle."
I personally like this allusion, and I wish we could redeem its edge a bit. It is being used a lot, though I'm not sure people understand its meaning. If you Google it, you'll discover it's been used as a name for Pizza Cafes, a greeting card company, and a comic strip.