An onomatopoeic word for something splashed or soaked with water or mud; wet and messy (often used for clothes, floors, or playing in puddles).
雨で靴がびちゃびちゃになって、足が冷たい。
My shoes are soaking wet from the rain and my feet are cold.
子どもたちは水たまりでびちゃびちゃ遊んでいた。
The children were splashing around in the puddles.
台所の床がびちゃびちゃなので、雑巾で拭いた。
The kitchen floor was all wet, so I wiped it with a cloth.