How to say [ its funny] in Japanese.
「可笑しい」　あるいは「爆笑」

Also, If I want to say that[ to get a Japan theme tattoo is a sort of irony] because in Japan Tattoo is a Taboo
「日本テーマの刺青するのは皮肉です。」does this sentence sounds weird or it makes ssense

Question

How to say [ its funny] in Japanese.
 「可笑しい」　あるいは「爆笑」

Also, If I want to say that[ to get a Japan theme tattoo is a sort of irony] because in Japan Tattoo is a Taboo
「日本テーマの刺青するのは皮肉です。」does this sentence sounds weird or it makes ssense

Answer

When you say 「funny」in Japanese you can say
「おもしろい」
「爆笑」＝「so funny 」
but I’m not Japanese teacher so I’m not sure. This is just my idea.

Answer

I can’t answer your second question, except to say that irony can be difficult to translate. But おかしい is certainly how you say “funny” (in both senses of the word).