The negative form of the 助動詞（じょどうし） (auxiliary verb) だ in Japanese frequently appears as
じゃない (an abbreviation of ではない). In 関西弁（かんさいべん）
じゃない is often replaced by
ちゃう.
ちゃう itself is actually just an abbreviation of 違（ちが）う, a common うverb meaning ‘to differ’.
ちゃう may be used directly after either nouns, or
な-Adjectives, to convey ‘is not (A)’.
-
今（いま）のエミの彼氏（かれし）ちゃう。
Isn't that Emi's boyfriend?
-
このドレス綺麗（きれい）ちゃう？昨日（きのう）買（か）ったの。
Don't you think this dress is cute? I bought it yesterday.
ちゃう may also appear in the past negative form. However, as it is a set expression (and not considered an actual conjugation of 違（ちが）う), it will not be conjugated like a regular う - Verb, but will become ちゃうかった.
-
タロウのお父（とう）さん関西人（かんさいじん）ちゃうかった？
Taro, wasn't your father from the Kansai region?
-
先生（せんせい）にだまされた。テスト少（すこ）しも簡単（かんたん）ちゃうかった。
The teacher tricked us. The test is not easy at all.
じゃない may also be replaced with
やない.
やない being the 関西弁（かんさいべん） equivalent of だ, with the
い-Adjective ない attached to it. Like
ちゃう,
やない is used after nouns, or
な-Adjectives.
-
あれ、ミオちゃんやない？
Hey, isn't that Mio chan?
-
見（み）て見（み）て、これ50%オフやった、お得（とく）やない？
Look look, this was 50% off, don't you think that's a good deal?
When conjugating in the past negative form,
やない follows the regular conjugation rules of ない, becoming
やなかった.
-
あの人（ひと）はさんまさんやなかった。ただのおっちゃんやった。
That person wasn't Sanma-san. It was just a middle aged guy.
-
便利（べんり）そうだったから買（か）ったのに、全然（ぜんぜん）便利（べんり）やなかった。
I bought this because it looked useful, but it was not useful at all.