ga-bidi-yow (W) ga-badi-yow (Kdj)
Or in IPA [gabiriyɔ] / [gabariyɔ].

kabirri- 'they (3+) non-past tense verbal pronoun prefix'
-yo verb stem 'to be lying down horizontal'. You can use any of these pronominal verbal prefixes on the verb stem (e.g. nga-yo, yi-yo, ngane-yo, ngarr-yo, kane-yo, ngune-yo, kabene-yo, karri-yo, ngurri-yo). Kabirri- is an arbitrary choice in Kunwinjku as a default prefix on the verbs (it would be kabarri- in Kundjeyhmi) because verb stems are not considered words in their own right. You must have a pronoun prefix on the verb stem.

There is a narrower verb to sleep -kodjkeyo (or just -keyo) which in Kuninjku and Kune (Maningrida) is -kodjdjeyo. The verb -yo is frequently used with the sense 'to be' as in some of the examples below.

Note that the verb -yo is a final form in other verbs such as the following:

-boboyo 'lie on one's stomach'
-bukirriyo or kodjbukirriyo 'to dream'
-lambarriyo 'lie on one's back'
-yirriyo 'lie across, lie in parallel'
-bolkngeyyo 'place have a name'

Verbs take different forms when the tense, aspect or mood changes (there's no space here to explain what aspect and mood are, but you can do your own online research):

COMMAND:
-yun, e.g. yi-yun 'you lie down'
PRESENT TENSE:
-yo, yi-yo 'you are lying down'
PAST PERFECTIVE:
-yoy or -yonginj, yi-yoy 'you slept'
PAST IMPERFECTIVE:
-yoy, yi-yoy 'you were sleeping'
IRREALIS (i.e. not real, e.g. negative)
-yuwirrinj, minj yi-yuwurrinj 'you didn't sleep'

Manme kayo?
(man-me ka-yo)
Is there any food?

A: Nawamud baleh wam?
(Na-wamud baleh wam)
Where has Nawamud gone?

B: Kayo.
(ka-yo)
She (or he) is sleeping (or at least lying down).

Konda yawurrinj kabirriyo.
(konda yawurrinj kabirri-yo)
This is where the young men sleep.

Nahni kabeneyo.
(nahni kabene-yo)
This man here is the husband (of her, literally 'this male one, they 2 sleep together').