1. Cut pineapple crosswise into 8 to 12 slices. Cut papaya crosswise into thin slices. Cut lime crosswise into paper-thin slices, discarding ends. Arrange fruit on plates.
2. In a 1- to 2-quart pan over high heat, stir corn syrup, lime juice, and cayenne until boiling, 1 to 2 minutes. Add tequila and immediately ignite (not near a vent, fan, or inflammables). Shake pan until flames die down. Spoon syrup over fruit.