The idea of the song's origin is a little funny from it being initiated from an anime character (Atom/Astro Boy). Anyways the song is kinda about just being a sweet dude. The "Oi" thing is just a rally call in general.

Comic anouncer guy: What is that mysterious
object soaring through the air?
Is it bird? (I dunno) 
Is it a plane? (The hell if I know)
Then what is it?
Atomic Boy!  

Hey what's that thing 
flying through the sky?
Is it bird? Is it plane?
No Atomic Boy!
Freind ta you and me,
with ability.
A super slick brutha'
Atomic Boy!

I wanna be a superhero!
Don't wanna be a super zero!
I wanna be a superhero!
Don't wanna be no super zero!
So rush the stage,
and bang your head.
Bang your head.
Bang your head!

Oi! Oi!
Atomic Boy!
Oi! Oi! Oi!
Atomic Boy!    (2x)

There's any need to panic.
There's no need to hide.
You know who ta call.
Atomic Boy!
He's the coolest guy.
Who could it be?
Everybody knows it's,
Atomic Boy!

I wanna be a superhero!
Don't wanna be a super zero!
I wanna be a superhero!
Don't wanna be no super zero!
So rush the stage,
and bang your head.
Bang your head.
Bang your head!

Oi! Oi!
Atomic Boy!
Oi! Oi! Oi!
Atomic Boy!    (2x)

Oi! Oi!
Atomic Boy!
Oi! Oi! Oi!
Atomic Boy!   (4x)