A fork of Rural Dictionary
Some one who is very small, not necassarily a child, just a small person. Generally used by people bigger than them.
Sometimes used as a title to some of these smaller people:
'Awwwww you're so cute, you little munchkin'
'Awwwww you're a munchkin and a half' (normally referred to a slightly taller munchkin/short person, therefore adding half a munchkin)
'You're the Munchkin of YAY!'