Add tequila, grapefruit juice, lime juice, and agave to a shaker and whip shake with some ice cubes.
Strain into the Collins glass filled with ice.
Top with club soda and very gently stir.
Garnish with a lime wheel.
You can find this cocktail at the following Walt Disney World bars and lounges: Coral Reef Restaurant · Crew's Cup Lounge · Crockett's Tavern Lounge · Grand Floridian Cafe · Gurgling Suitcase · Mama Melrose's Ristorante Italiano · Martha's Vineyard Lounge · Olivia's Cafe · Outer Rim · Sanaa · Territory Lounge · The Hollywood Brown Derby Lounge · The Turf Club · The Wave · Victoria Falls Lounge · Whispering Canyon Cafe