• Prepare the Glass: If desired, rim a highball or Collins glass with salt. To do this, rub a lime wedge around the rim of the glass, then dip it into a plate of salt.
• Mix the Ingredients: In a shaker, combine the tequila, fresh lime juice, grapefruit juice, watermelon juice (or muddled watermelon), and simple syrup (if using). Fill the shaker with ice and shake well until chilled.
• Strain and Serve: Strain the mixture into the prepared glass filled with ice.
• Add Soda: Top off with club soda.
• Garnish: Garnish with a slice of watermelon and a lime wheel.

Tips:

• For the watermelon juice, you can blend fresh watermelon chunks and strain the juice, or muddle watermelon directly in the shaker.
• Adjust the sweetness by adding more or less simple syrup based on your taste preference.