He spoke defiantly to his boss and handed in his resignation.
That politician is famous for speaking sharply at press conferences.
Ateji spelling; the kanji are used phonetically. This is the standard written form for the word.
Kana spelling is common in everyday writing, especially when the ateji kanji are not needed.
The kanji 啖呵 are ateji (phonetic equivalents) and do not contribute meaning. The word likely derives from a mimetic or sound-symbolic origin, but the exact derivation is uncertain.