also: しいしい
noun
Children's word for urine or urination; used with small children in informal, family settings.
赤ちゃんがしーしーをした。
The baby did a wee-wee.
トイレでしーしーしようね。
Let's go pee-pee in the toilet.
Reduplicated mimetic word from the sound of urination; the exact derivation is uncertain.