Twonkie
From Jimmy Neutron Wiki
Twonkies are a life-form from a comet Twonkus3. They are small cute beings, but when they hear any music they turn into vicious monsters. When some twonkies aren't in freedom, or trapped they turn into one big almost indestructible monster.They are similar to Mogwais eating after midnight to turn into Gremlins when Twonkies listen to music to get bigger.
Reproduction
A twonkie coughs out babies, but nothing more is known about this process.
Reaction to external sounds
Twonkies turn angry when they hear music, but only if it's pleasant. For example Sheen's singing makes them sleep.
In various episodes Twonkies can be seen in various places.
