I happen to like this phrase which gets its origins from the UK.  If you're not familiar, it is used to describe something that would be a simple set of instructions such as:

"Gather up all the ingredients, put them in a bowl, mix, and Bob's your uncle, you have cookie batter." 

I was curious one day where exactly why/how the term came to be.  Come to find out there isn't one explanation that has been decided upon as the one true origin.  A quick search of wikipedia reveals these possible origins: