In an appropriately large container, combine ingredients for pineapple tequila.
Leave for at least a week, stirring occasionally.
Strain the alcohol from the container.
Separate the pineapple from the vanilla beans and put the pineapple in the freezer, in freezer bags, in 1 cup sized portions.
(You can start a new batch by putting more tequila and more pineapple in, re-using the vanilla beans.) At party time, make the margaritas.
Using your blender, whir the margarita ingredients, including 1 cup of the pineapple chuncks and 1 cup of the tequila until smooth and frozen, adding ice as is necessary for your preferred strength and texture.
Serve in glasses, rims encrusted with either sugar or salt (your preference), with plenty of chips and salsa nearby.
