also: とんちき
noun
Colloquial, mildly derogatory term for a stupid or foolish person. Often used in a teasing or exasperated tone.
あいつは本当にトンチキだな。
That guy is a real idiot.
トンチキなことを言うなよ。
Don't say stupid things.
アホ is similar in meaning but more strongly associated with the Kansai dialect; トンチキ is not region-specific.
Katakana spelling is the usual written form for this colloquial word.
Hiragana spelling; also common.
Ateji kanji form; rarely used.
The origin is uncertain. The kanji 頓痴気 are ateji (phonetic equivalents) and do not contribute to the meaning.