The margaritas in Dallas tend to blur together (especially when you drink them back to back). They're mostly green, they're made with cheap tequila and they all smell like a hangover. At Stampede 66, none of these are true. The margarita that's made on a cart beside your table after you order it is more like a science experiment than any lime-tinged margarita you're used to. Prickly pear fruit, lime and candied jalapeño join liquid nitrogen for a misty show that will take you back to chemistry lab in high school. Except you're of legal age now, so put the isopropyl alcohol down and get to drinking.