[ShiShiLeo]

Aruto ja naito is more of a nonsensical catchphrase. It doesn't really have a direct 1:1 translation but the feeling of it is like "It wasn't me!" The joke part is that "me" is him saying his own name therefore implicating himself.

So like Kiwami said, it is as if he is simultaneously admitting to something and also claiming innocence; in most cases a bad joke that he won't take credit for unless you thought it was funny then he will take credit for it.

An American equivalent is like when you tell a bad joke and then immediately say "just kidding, but for real though..."