Halve 1 small watermelon and scoop the flesh out of one half into a bowl (you need about 375-400g). Pick out any black seeds. Purée the flesh using a hand blender or in a liquidiser. Fill ice lolly moulds three-quarters full with the purée, push the sticks in if you are using them, and freeze for at least 3 hrs, or overnight. Tip any remaining purée into an ice cube tray and freeze it.
Peel 3 kiwis and cut the green flesh away from the white core, discarding the core. Purée the flesh. Add a layer of about 4-5mm to the top of each lolly and refreeze for 1 hr. Add some green food colouring to the rest of the purée to darken it to the same colour as the watermelon rind. Pour a very thin layer onto the top of each lolly and freeze until you want to eat them.