Add water and sugar in a small saucepan over medium heat, and swirl until dissolved, about 3 minutes.
Allow to cool for 5 minutes, and add the lime juice, green food coloring and Chia seeds. Transfer to a bowl, cover, and refrigerate overnight.
Remove from refrigerator, and add tequila, stirring until well incorporated.
To make the rambutan "cups", take a paring knife, and cut through the skin of the rambutan all around, being careful not to cut the flesh of the fruit that lies about 1/8" underneath the skin. Remove the fruit, and reserve for another use.
Place halves of rambutans on your serving platter, making sure that they're all level. Stir the shooter mixture again, and transfer to a vessel that you can easily pour out of, like a pyrex glass measuring cup (with a spout).
Carefully pour the shot mixture in the rambutan halves. Serve to your guests!
The little monster guy in the pic is a kiwano melon. I took a paring knife to make eyes and a mouth - the insides are yellowish green and great for the effect! Rambutan skins were used for the hair and eyebrows.