A rabbit/chipmunk (whichever you prefer) looking, alienic mutant form of creature which exists deep in the sewers.
This particular gremlin has only been speculated to exist as few records or eyewitnesses are readily available to confirm this ancient myth.
Most eyewitnesses do not live to tell the tale after meeting this particularly horrendous monster.
The majority of the unfortunates who encounter a Yeyeng do not live to tell the tale. It is believed that the Yeyeng consumes its victims by eating them inside out.
The remaining survivors are better off dead, having suffered a tremendous trauma. They are regarded as the mentally retarded people among our society and now reside in various mental institutes.
Omg you totally look like a Yeyeng!
Tom : What're you wearing for Halloween?
Jerry : A Yeyeng mask.
Jack : Why is mommy in hospital?
Jill : She saw a Yeyeng.