The Boomer

From wikipedia

A hugely obese Infected that can projectile vomit at The Survivors, blinding them and attracting swarms of nearby Infected to them. When Boomers die they blow up, creating large amounts of gore and viscera, this also attracts NPC infected to the area in which the Boomer exploded. Boomers can also drop from tall buildings into/onto a group of survivors, and once they impact on the streets, they "pop" exploding in the before mentioned manner having the same effect as the vomit attack, this skill could serve as an effective method for ambushing the survivors. As of recent game play changes, the Boomer no longer damages when detonated by neither gunfire nor falling, but hinders survivors' sight and attracts large amounts of the infected horde.