クタクタだよ。

くたくただよ。

I'm tired.

クタクタだよ。

Kutakuta da yo.

くたくた (くたくた、ぐたぐた、ぐだぐだ)

exhausted; tired; withered; worn out; boiling until shapeless or mushy; tediously; repetitively; wordily

だ (だ)

be; is; indicates past or completed action; indicates light imperative

よ (よ)

indicates certainty, emphasis, contempt, request, etc.; used when calling out to someone; used to catch one's breath or get someone's attention; yo!