むちゃくちゃ

〈場ば所しょ〉が無む茶ちゃ苦く茶ちゃになるfor a place to become a total mess
台たい風ふうで庭にわが無む茶ちゃ苦く茶ちゃになった。
The garden became a total mess because of the typhoon.
〈物もの〉を無む茶ちゃ苦く茶ちゃにするto wreck or ruin something completely
子こ供どもがおもちゃを無む茶ちゃ苦く茶ちゃにした。
The child completely wrecked the toy.
無む茶ちゃ苦く茶ちゃな〈事こと〉を言いうto say something absurd or unreasonable
彼かれは会かい議ぎで無む茶ちゃ苦く茶ちゃなことを言いった。
He said something completely unreasonable at the meeting.
無む茶ちゃ苦く茶ちゃに〈形けい容よう詞し〉extremely; incredibly (intensifying an adjective)
今日きょうは無む茶ちゃ苦く茶ちゃに忙いそがしい。
I'm incredibly busy today.

Kanji

めちゃくちゃN3
めちゃくちゃ and 無茶苦茶 are nearly interchangeable, but めちゃくちゃ feels slightly more casual while 無茶苦茶 can sound a bit more emphatic or old-fashioned.
でたらめN3sense 1
でたらめ stresses that something is random or made-up, while 無茶苦茶 stresses unreasonableness, excess, or chaos.
支し離り滅めつ裂れつ sense 1
支離滅裂 is a more literary term for something logically incoherent, whereas 無茶苦茶 is the everyday word for the same kind of nonsense.
乱らん暴ぼうN3sense 2
乱暴 describes rough or violent behavior specifically, while 無茶苦茶 more broadly covers reckless or excessive action of any kind.
混こん乱らんN3sense 3
混乱 is a neutral, formal word for confusion or disorder, while 無茶苦茶 conveys the same idea more colloquially and often with a sense of ruin.

むちゃくちゃUsage38%
Standard hiragana spelling; the most common written form.
無む茶ちゃ苦く茶ちゃUsage43%
ateji (phonetic kanji usage)
Ateji kanji spelling; rarely used in modern writing. The word is almost always written in kana.
ムチャクチャUsage19%
kana-only spelling
Katakana spelling used for emphasis or in informal writing.

An emphatic, rhyming expansion of むちゃ, with くちゃ reinforcing the sense of disorder or excess. 無茶苦茶 is an ateji spelling.