If you want your political action song to connect with people, it's important to create a dialogue with the listener. Observe:

Everybody get up

Oh, everybody? I'm part of everybody, why should I get up?

It's time to slam now

Slam? That doesn't sound pleasant, why would I want that?

We've got a real jam going down

A jam? I don't want to get into a jam either.

Welcome to the Space Jam

A jam in space? Do they mean outer space? I'm going to need more information about this.

Here's your chance

My chance? Oh no, I don't want to miss out on anything, I'd better pay close attention to whatever comes next

Do your dance at the Space Jam

Oh! They mean "slam" and "jam" figuratively. I don't have much interest in dancing, but now I'm invested in the song, so I might as well keep listening.

Come on and slam, and welcome to the jam

They sound really welcoming. Maybe I should join them. It couldn't hurt to try, right?

Come on and slam, if you wanna jam

You know what? Now that I've had time to mull it over, I think I do want to jam. Invitation accepted. 🕺

As you can see, the listener began with no interest in dancing, to the extent that they found the unknown terminology vaguely threatening; but by getting their attention with a direct call to action, piquing their interest with a seemingly contradictory juxtaposition ("space jam") and doling out new information piecemeal, the listener warms up to the idea. Once they're on board with the dancing, the song's much more likely to succeed in its ultimate goal: getting their help in the intergalactic basketball war.

If the song started out like this:

Everybody come dance
And play basketball
It's time to fight hard
Against the aliens
That want to conquer Earth
Maybe we'll all die

It'd be a lot less likely to gain their support. Most people won't even dance unless you encourage them in just the right way, you definitely don't want to jump straight into death rays and draining threes 🦝