Slice 2 thick pieces (discs) of watermelon from the middle of the fruit and remove the rind from both pieces. Cut each into 6 to 8 slices (wedges), depending on the size of the watermelon.
Pour the tequila into a large bowl and soak the watermelon slices in the alcohol for 15 minutes, making sure each slice is completely submerged. One by one, slide an ice-pop stick at least halfway into each slice.
Spread the slices on a parchment-lined baking sheet so they aren't touching. Freeze until completely frozen, 3 to 4 hours.