Not many objects generate immediate goodwill the way a flask does. It's sort of a handshake in liquid form, one that's both neighborly and conspiratorial. Pull a hip flask out of your pocket and offer it to someone — a friend, an enemy, a complete stranger — and together you're breaking a taboo against drinking in public. Perhaps that's the beauty of a particularly fetching flask: In addition to its being a refined accoutrement for a fishing trip, a backcountry ski tour, or even a concert, it's also a thoughtful offering that creates an unspoken bond. It's a boozy pact to have a little fun together.
And sure, you can fill your flask with some mellow single-malt scotch or a small-batch bourbon, but spirit-forward cocktails are a far more heartwarming, novel offering. The key is to make them simple: Use no more than three ingredients, and stay away from anything with citrus juice, which can damage a flask's lining. Just premix and funnel in. These two flask-fillers pack a punch, just like a good conspiracy should.