According to cocktail legend, 
the Bronx cocktail was invented in the bar of the Waldorf Astoria as a nod to the Bronx Zoo.
I don’t quite get the connection between confined animals and what is basically a perfect orange-infused martini. “Perfect” being the mixology term for a drink which includes equal parts sweet and dry vermouth (shout out to my friend Andy P. for providing me with that crucial bit of information some time ago).
Ingredients:
- 1 jigger DRY GIN
- 1/2 pony ITALIAN VERMOUTH
- 1/2 pony FRENCH VERMOUTH
- 1/8 ORANGE
- ORANGE SLICE
- SHAVED ICE
In a mixing glass, muddle 1/8 of an orange. Add ice, gin and vermouths. Shake well and strain into a cocktail glass. Serve with an orange slice.
Notes:
All the other versions I found of this cocktail simply call for a 1/2 ounce to one ounce of OJ, so I enjoy the fact that Caulkins specified muddling up a bit of actual orange in his recipe. Not only do you get the sweet tangy-ness of the fresh juice, the muddling also releases the oils in the peel; so the extra kick of pure orange essence is really bright and satisfying.
The “perfect” balance of vermouths round out the flavor nicely, and serve as a reminder that you are, in fact, drinking a martini. They also ratchet up the alcohol content a little, so sipping a Bronx Cocktail is as least as much fun as a barrel of monkeys. 
Ah-ha! See that? I managed to work confined animals in there, after all.