A swizzle is a (typically) rum-based drink, served on crushed ice and stirred with a special swizzle stick, which has a flared, spiked bottom to help agitate the drink. You don’t really need a special stick; a normal barspoon is fine.
This particular swizzle is a favorite house cocktail at Central Standard in Austin. It’s a pretty straightforward rum swizzle, distinguished mostly by the use of lemon juice instead of lime, and by the gorgeous topper of blood-red Angostura bitters.
The bitters are more for scent than taste, since the drink is usually served with a straw. Our measurement is based on the size of the Collins glasses we used; you’ll need enough dashes to ensure that the top of the drink is completely soaked in the stuff.