Line a 9-by-9-inch baking dish with plastic wrap.
Combine Jell-O powder and 2 1/2 cups boiling water in a large bowl and stir to dissolve. Add tequila, lime juice, and triple sec and stir until well combined. Pour mixture into prepared baking dish and refrigerate at least 3 hours or up to 24 hours.
Once Jell-O has set completely, turn out onto a clean surface and peel off plastic wrap. Cut into 1-inch cubes and serve on cocktail picks. Cheers!
* Lose the plastic cups. Cocktail picks make these jiggly cubes easier to eat.