Less than a quarter the size of a Lumpty, these more recent variants are notoriously energetic, constantly vibrating at high speed to ricochet and tumble on their stiff spikes. They produce a smaller and weaker explosion than their larger predecessor, but scatter an oil that immediately ignites on contact with air and will continue to burn where it lands for several hours.

   A Bumpty forced to stop moving will invariably detonate with sheer frustration. It is not known if they have even the limited vocabulary of a Lumpty, as no Bumpty has ever stopped giggling long enough to formulate a complete word.