gung-ho

/G AH1 NG OW0/
adjective
  1. 1

    Overly enthusiastic or energetic.

    โ€œNo matter how gung ho you are when you start, you will tire as you become mired in details.โ€

  2. 2

    Cocky, undisciplined, contemptuous of rules

Source: https://en.wiktionary.org/wiki/gung%20ho, https://en.wiktionary.org/wiki/gung-ho