Don't skip the pineapple juice, as this is what changes the color of the drink when mixed with the blue curacao. You could try mixing it with orange juice if preferred. You can use pineapple juice from a can or in a bottle.
Be sure to shake your pineapple juice before adding it to the rest of the ingredients. Otherwise, the color can settle into a blue colored drink instead of green leaving the thinner part of the juice at the top.
Vodka pairs nicely with so many fun cocktails, but if you don't fancy it you can substitute with Triple Sec, white rum, or tequila.
Depending on how deep in color your pineapple juice is, you may end up with a slightly more blue-hued drink. Feel free to add a drop or two of food coloring if needed.