一古脑儿
yī​gǔ​nǎo​r

completely

  1. 一 yī numeral
    whole
    whole; entire; throughout; all
  2. 古 gǔ
    opaque (segment carries no independent meaning)
  3. 脑 腦 nǎo noun
    brain
    The brain of a person or animal; the organ in the head that controls thought and movement.
  4. 儿 兒 r particleaffix
    [erhua suffix]
    A suffix attached to a word to form a retroflex ending, often indicating a small size, a sense of familiarity, or turning a word into a noun.