expression "caught between a rock and a hard place"

What is the origin and definition of the expression "caught between a rock and a hard place"? I also heard it in a situation where it could have had a jocose double sense, but I may have misunderstood.

The expression is used when there is a dilemma or only two equally difficult decisions. It can be implied where there is a mandatory to make a choice between at least two unpleasant choices.

The origin, according to Phrases Dictionary, is derived from an economic issue where workers face underpaid wages ( a rock) and unemployment (hard place). The full version of the story can be found in the reference.

Other origin worths mentioned is the Greek mythology "Between Scylla and Charybdis", where Odysseus has to take a route between six-headed monster Scylla and the whirlpool Charybdis. For further reading on Wikipedia.

According to phrases.org.uk:

The earliest known printed citation of 'between a rock and a hard place' is in the American Dialect Society's publication Dialect Notes V, 1921:

"To be between a rock and a hard place, ...to be bankrupt. Common in Arizona in recent panics; sporadic in California."

The 'recent panics' referred to in that citation are undoubtedly the events surrounding the so-called US Bankers' Panic of 1907. This financial crisis was especially damaging to the mining and railroad industries of the western states.

More information on the concept of "between X and Y" is found on Wiktionary:

Related to the concept of the Ancient Greeks: "between Scylla and Charybdis." [...]

I therefore highly doubt it has much to do with the bible, but I must confess I haven't checked.

Hope this has been helpful.