無頭無尾 [无头无－]

Jyutping mou4 tau4 mou4 mei5
Pinyin wú tóu wú wěi

Definitions (Wiktionary)
  1. phrase, figuratively, idiomatic, of a matter
    to have no clue of the reason or cause; to be unclear; to be incomprehensible; to be nonsensical
  2. phrase, figuratively, idiomatic
    to be chaotic; to be messy; to be all over the place