Mix Tajin and sugar on a small plate. Rub the rim of a cocktail glass and dip into the mixture to rim the glass, shaking off any excess. Add ice to the glass and set aside.
In a shaker filled with ice, add the tequila, pineapple liquor, and lime juice. Shake for 15 seconds and then strain into the prepped glass.
Top the glass with the pineapple Jarritos and garnish with a lime wedge and pineapple chunk. Enjoy!