Cut the pineapple flesh into 1cm dice and divide between 8 x 100ml ice lolly moulds. Put the condensed milk and pineapple juice in a food processor and blend until smooth. Transfer to a jug and carefully pour into the ice lolly moulds, filling them 1cm below the top (the mixture will expand as it freezes).
Put the tops on the moulds and insert the sticks. Freeze for 8 hours or overnight, until set. To unmould, dip the moulds in warm water for 10-15 seconds and serve immediately.