I'm not sure if I'm just imagining things or if I remembered things wrong,
but is there some kind of colloquial dialect where sentences end in "-jai?"
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Sign up to join this communityYou are not imagining things. (The tougher) Kansai male speakers do say 「~~~じゃい!」 in colloquial speech. Only the 「い」part is a particle -- an emphatic sentence or phrase ender. And じゃ = だ.
The Standard counterpart would be だよ or だい.
The Kanto countepart would be だい or でぇ.
じゃい
in Kansai. Although in all my time, I only heard おおきに
by an お婆ちゃん exactly once.