Among descriptions of political libertarianism, "socially liberal, fiscally conservative" probably takes the prize for both simplicity and frequency of use.
It's especially useful in an election year. The Libertarian Party's presidential candidate generally faces high media access barriers and limited opportunities to reach "low-information voters" with the elevator pitch for smaller, cheaper, less intrusive, and less warlike government.
It's pithy. It's easily, if not necessarily accurately, understood. It associates itself with the two of the most mainstream/popular American political tendencies. What's not to like?
I don't use the slogan much, though. I don't really consider it very accurate. I know many "socially conservative" (often, though not always, due to their personal religious beliefs) and "fiscally liberal" (often, though not always, due to their historical analysis of phenomena like corporations and taxation) libertarians. And an op-ed gives me a little bit more room to elaborate than a politician's elevator pitch. So hang in there with me, please.
What differentiates libertarianism from other political ideologies isn't just a utilitarian or consequentialist claim as to "what works best."
What differentiates libertarianism from other political ideologies is a moral claim: The claim that it is wrong to initiate force.
That's a moral claim you probably grew up with as an individual.
The people who shaped your worldview as a child --- parents, teachers, etc. --- almost certainly taught you libertarianism as a matter of basic individual morality. In the words of libertarian author Matt Kibbe: "Don't Hurt People and Don't Take Their Stuff." Words to live by.
Libertarians extend that moral claim to everyone and to all organizations, including government.
Just as it's wrong for me to steal $50 from your wallet, it's wrong for government to steal $50 from your paycheck.
Just as it's wrong for me to burn down your house or shoot you other than in self-defense, it's wrong for government to conduct itself violently against the non-violent.
To the extent that a "social contract" can really be said to exist, that's the whole of it --- don't hurt people and don't take their stuff, in return for which we need not tolerate others hurting us and taking our stuff.
You're free to believe whatever you want to believe, as long as you don't forcibly inflict those beliefs on others.
Libertarianism is a "deontological" (morality-based) rather than "consequentialist" (outcome-based) position.
Happily, however, it's not a fiat iustitia ruat caelum --- "let justice be done though the heavens fall" --- position, because its application won't bring the heavens down. It really DOES produce better outcomes than state edict backed by force.
Unhappily, it doesn't easily translate to the electoral politics "elevator pitch"/"low-information voter" environment.
But if you've read this far, you're an off-the-elevator "high-information voter" now. Remember, come November.