The bullfrog doesn't stray far from a pond or oasis, mainly lurking underwater and waiting for a fish or rodent to wander by. However, when said rodent gets too close, the bullfrog will leap out of water, hooking it's tusks underneath it's prey and leading it up into the air, snapping into it.
Kick it. Hard.
Hope it doesn't bite you.
They don't bother bigger things usually. I know it's ugly, just try not to insult them.