Squeeze all the juice out of the oranges and strain it into the cocktail shaker.
Cut jalapeno into a few rings and using a garlic press, squeeze some jalapeno juice into the shaker as well. (I find that 3-4 jalapeno rings is enough but you may like it spicier.)
Add tequila and triple sec to the shaker. Shake well.
Strain the margarita mixture into the glasses. You can serve it over ice or straight up.