Cut pork shoulder into small chunks, about 2" x 4".

Squeeze the juice from the oranges and limes into a bowl.

Place pork in a wide metal pot oven along with the cloves of garlic. Add the orange and lime juices. Add the chicken stock so that the pork is just covered (a few chunks sticking out is fine). Add sea salt.

Bring to a boil, then cover and simmer for about two hours, stirring occasionally.

Uncover and let boil down for about 30 minutes until liquid is reduced by half, stirring occasionally.

Add tequila and increase heat to medium, continuing to let boil down until the liquid has boiled off and the pork is now starting to fry a bit in its own fat. Allow small chunks to brown on the bottom of the pan, careful not to let them burn. Scrape up browned bits from the bottom of the pan with a metal spatula and gently stir them in.

When the liquid has boiled off but while the meat is still moist and some of it has gotten crispy, remove from heat. Add salt to taste if desired.

If you're going to the party right away, you can just cover the pot and bring it as-is so that the meat stays warm and moist. If you're going later that day or the next day, you can store the meat in an airtight container in the refrigerator and reheat it in a covered dish before you bring it to the party, to let the fat melt again. Once it's been reheated, it will taste great at room temperature; it's even better if you can keep it warm until the party.