The Legions of Terror are well known for their fondness for writing songs about basically everything they do. This tendency is at its strongest with major or amusing victories. It is, unsurprisingly, popular with the Legions and unpopular with Callowans.
In "Amadeus' Plan" (Book 7, Chapter 21), the full lyrics are revealed.
The lyrics are as follow:
Boot goes up and boot goes down:
There goes their callow crown
And no matter how high the walls
We’re all gonna make them fall
They can send us their pretty Knight,
Their killer all decked in white,
Only now we’ve got one too –
And he always gets his due
They got a wizard in the West
But no matter how he’s blessed
We got a Warlock in the Tower
Who’ll use his bones for flour
Let them keep their priestly king
Cause no matter how sweet he sings
We’ve got an Empress black as sin
Who’ll take his throne and grin
We’re the Legion and the Terror
They’re in the right but we’re meaner-
So pray hard boy, and pay your toll –
We’re gonna swallow the world whole.
The final line of the song is usually bellowed.
The Song is also called Swallow the World by some.