How do you use ”～じゃんよ。” and what exactly does it mean?

Question

At the end of sentences in casual form I know you can use ～じゃない or ～じゃん to say "~isn't it?" similar to ～ね. And I know ～よ at the end of a sentence can be used like "I tell you" or for emphasis, but what happens when you use ～じゃんよ at the end of a sentence, like in the titles of Space Dandy episodes (the examples below)? The official English episode titles all end with ", baby" so I feel like it's a speech pattern of someone who considers themself kinda cool. E.g.

流れ流されて生きるじゃんよ
Live with the Flow, Baby

幻の宇宙ラーメンを探すじゃんよ
The Search for the Phantom Space Ramen, Baby

騙し騙される事もあるじゃんよ
Occasionally Even the Deceiver Is Deceived, Baby

Answer 1

The titles are non-standard Japanese (they are creative sentences). I for one think the translations are as good as it gets.

In normal contexts they are used like this:

受験失敗したのは自分のせいじゃんよ
(Lecturing) The reason you failed was your own fault, isn't it hey?

安っぽい店で飲みたいこともあるじゃんよ
(Defending) Sometimes you wanna drink in a cheap place, don't we hey?

It generally sounds confident because you are asserting the fact, which is has a patronizing effect. I think that's why the translation adds "baby", and I think it does reflect the tone pretty well.

Answer 2

じゃん/じゃんよ is a kind of dialect around Tokyo, Kanagawa and Yamanashi Prefecture. Many young people (including me) commonly use じゃん in casual conversation. I feel じゃんよ is less popular than じゃん.

(1) talking common topic

「明日パーティーあるじゃん？何時に集合にする？」
("You know, we're gonna party tommorow? What time can we meet together?")

(2) expressing feeling

「これおいしいじゃん！」
("Yummy!")

(3) (casually) blaming

「そんなことしたらだめじゃん」
("You shouldn't do such thing.")

(4) asking someone's approval

「やっぱりそう思うじゃん？」
("You think so too?")