I've heard the phrase "don't spend it [money] all in one store" a number of times, virtually always in a joking manner. Where did it originate from and has it always been said as a joke?
Google books says that the term originates from here's a ha'penny. The definition it gives for this is:
"A joking phrase that accompanies the gift of a small amount of money to someone, usually a child."
The origin and reasoning for this phrase can be seen in lots of different situations. Quite possibly one of the earliest examples of a situation that would of provoked this statement is the Prodigal Son.
The prodigal son runs off and spends all of his inheritance in a very short amount of time (all at once) and then is left with nothing. This results in him going back to his fathers house and falling on his mercy. Something not deemed desirable. Again lending itself to the saying "don't spend it all at once or in one place."