An expression I learned to love during the time I lived in England was “Bob’s your uncle!” Thanks to international sports events, the saying is better known in the States now than it used to be.
You tack it onto a set of instructions that are meant to lead to an easy solution:
Question: How do I make this work?
Answer: Put Tab A into Tab B, turn this little screw, and Bob’s your uncle!
Question: Can you direct me to the Green Man?
Answer: Carry on to the corner, turn right, go past the greengrocer’s, turn right again, and Bob’s your uncle!
The expression’s origin is shrouded in mystery.
A frequent explanation cites the nepotism of British Prime Minister Robert Cecil, Lord Salisbury, who appointed his nephew Arthur Balfour to the post of Chief Secretary for Ireland in 1887. The idea is that if your uncle happens to be the Prime Minister, anything is easy. The difficulty with this explanation is that the earliest known use of the phrase “Bob’s your uncle” is from 1932.
Another possibility offered is that it may derive from 18th thieves’ slang: “all is bob,” meaning “all is safe.”
The Phrase Finder suggests that a music hall song published in 1931 may have been the source:
Bob’s your uncle
Follow your Uncle Bob
He knows what to do
He’ll look after you
I think it’s more likely that the song derived from the saying.
We’ll probably never discover the origin of this delightful expression. Its lack of discernible sense suggests an origin in the folk etymology that causes a misheard foreign word or phrase to dwindle into pronounceable English nonsense. For example:
hocus-pocus: a scrambled version of Latin Hoc est corpus meum, “this is my body,” words from the Catholic Mass
kickshaw: English approximation of French quelque chose, “something” (A kickshaw is a doodad, a whatnot, a thingamajig, a something or other.)
Smackover: Arkansas place name thought to be from French chemin couvert, “covered way”
love: tennis score notation (meaning “zero”), from French l’oeuf, “egg” (the shape of a zero resembles that of an egg)