Freeze 3 pigs with one ice bird
Ice birds are light blue in color and freeze everything around them when they explode. This achievement is most easily earned on Level 2-23. Fire your first bird (ice bird) to the large tower containing 6 pigs, arching him through the gravitational fields. Just before he lands, tap the screen to explode the bird, freezing the pigs in the area. You should have no problem getting three or more pigs with a well-placed shot