めちゃくちゃ absurd, excessive, messed up…
Though normally written in kana alone there are kanji for this word which reveal it’s origin.
滅茶苦茶/目茶苦茶 － めちゃくちゃ
A teacher I know explained about ‘bad tea’. If the water used to make tea is too hot then the flavour will be destroyed. On the other hand, if the water isn’t hot enough then the tea won’t taste good. If you look carefully at the kanji then you can start to get an idea behind it’s meaning.
I’m sure I heard this word first in an English song. Was it by Mary J.Blige?