From Zelda Wiki, the Zelda encyclopedia
Fruit Balloons are balloons of varying sizes that Link must hit and pop in order to get points. They are found in Twilight Princess and Link's Crossbow Training. In Twilight Princess, Link can play Plumm's game only as a wolf and score points for them. In Link's Crossbow Training, they are found flying over Hyrule Castle Town. Each of the fruit balloons have different point values; the largest having the least points, and the smallest having the most points. Link can also hit fruit balloons of the same type in a row to score more points than normal.
In Twilight Princess the balloons are classified by color/fruit:
Hitting balloons of the same size in a row results in a score multiplier that doubles with each successive hit, but if Link interrupts his combo by hitting a balloon of a different size, his score multiplier will reset and balloons will go back to their original value.