Back in Austin, Trudy's has an epic drink called the Mexican Martini. Epic enough such that there's a relatively strict 2/person limit. Luckily, there are multiple Trudy's in town...

The recipe is somewhat contentious. Many have tons of orange juice and even sprite in the recipe, but I remember hearing from a trusted source that there was definitely a bit of rum in the mix. You're aiming for a strong and slightly briney margarita, shaken and served up.

Juice of 2 limes
3 oz tequila (or split with mezcal)
1 oz cointreau
1 oz rum
1 oz orange juice
dash of olive brine

Serve in a margarita or cocktail glass, rimmed lightly with salt. Garnish with pepper-stuffed olives.

Some sources:
http://hilahcooking.com/how-to-make-a-mexican-martini/
http://www.tastebook.com/recipes/986092-Trudy-s-Mexican-Martini