What's with dinosaurs in Vietnam?

Question

There's an awesome song by Black Sabbath called Into the Void. It's been covered by a few bands, including Monster Magnet.

In Monster Magnet's version, which is also super awesome, there are additional lyrics. He keeps talking about dinosaurs in Vietnam. What? Why?

Here are the original lyrics (from Google Play Music):

Rocket engines burning fuel so fast
Up into the night sky they blast
Through the universe the engines whine
Could it be the end of man and time
Back on earth the flame of life burns low
Everywhere is misery and woe
Pollution kills the air, the land, the sea
Man prepares to meet his destiny

Rocket engines burning fuel so fast
Up into the black sky so vast
Burning metal through the atmosphere
Earth remains in worry, hate and fear
With the hateful battles raging on
Rockets flying to the glowing sun
Through the empires of eternal void
Freedom from the final suicide

Freedom fighters sent out to the sun
Escape from brainwashed winds and pollution
Leave the earth to all its sin and hate
Find another world where freedom waits

Past the stars in fields of ancient void
Through the shields of darkness where they find
Love upon a land a world unknown
Where the sons of freedom make their home
Leave the earth - to satan and his slaves
Leave them to their future in their graves
Make a home where love is there to stay
Peace and happiness in every day

Here's the modified Monster Magnet version (from LyricsFreak):

Oh!
Everywhere is unreal.
The fame of my birth known.
Oh!

Those dinosaurs in Vietnam!
Those dinosaurs in Vietnam!
Those dinosaurs in Vietnam!
Aah

Come on and show me.
Come on and show me.
A man who has to leave his destiny.
A man who has to leave his destiny!
Aah

Come on and show me!
Show me now!

Yeah the techno sluts are dancin' in hell.
The techno sluts are dancin' in hell.
Oh yeah!
Into the twentieth century yeah!

Aw poor baby.
Poor baby.
Yeah you've all bit the dust, ha ha.
Ain't no soul comin' back motherf***er.

Woo
Aah

Into the void
Aw
Woo!

Rocket engines burning fuel so fast,
Up into the night sky they blast.
Through the universe the engines whine,
Could it be the end of man and time?
Back on earth the flame of life burns low,
Everywhere is misery and woe.
Pollution kills the air, the land and sea.
Man prepares to meet his destiny.

Into the void!
Yeah!
Woo!

Rocket engines burning fuel so fast,
Up into the night sky so vast.
Burning metal through the atmosphere,
Earth remains in worry, hate, and fear.
With the hateful battles raging on,
Rockets flying to the glowing sun!
Through the empires of eternal void,
Freedom from the final suicide!

Into the void!
Yeah!
Down to the void!
Woo yeah!
Aw yeah!

You're a f***ing genius!
That's right!

Dinosaurs in Vietnam.
Dinosaurs in Vietnam.
Dinosaurs in Vietnam.
Dinosaurs in Vietnam.
Oh!

That's all that can be saw. Ha ha!
Oh yeah that's right.
Yeah

As you can see, he repeats "dinosaurs in Vietnam" quite a few times. Why? What does that have to do with anything else? They've essentially omitted the last two verses and replaced them with this other stuff.

Answer 1

Dave Wyndorf, songwriter, lead vocalist, and a guitarist for Monster Magnet, explains in an interview with Adam De Ville for Collide:

Adam De Ville: “Dinosaurs in Vietnam!”

Dave Wyndorf: Yeah! I just pictured a T-Rex stomping through Vietnam and chomping everything up during the war. I made it all up on the spot and Dave Sardy was totally into it - he knew what I was going for. The original version must have been like half an hour long and it was cut down.