There seems to be an unintended interaction between the Volatile Zombie passives ‘Repulsive Vomit’ and "Leap Attack’.
The Zombie will leap to it’s target, begin vomiting, then bounce up and down over and over again, interrupting the vomit each time. It even seems to interrupt most of their basic melee attacks, as they bounce up and down excitedly but nothing dies.
The normal behavior of a Leaping zombie is to leap and immediately self-detonate.
The normal behavior of a Vomiting zombie is to run up, begin vomiting which rapidly drains their health, and then explode.
Leaping Vomiting zombies… bounce.