Cock Up Your Beaver

By Robert Burns

I.

When first my brave Johnnie lad
Came to this town,
He had a blue bonnet
That wanted the crown;
But now he has gotten
A hat and a feather, -
Hey, brave Johnnie lad,
Cock up your beaver!

II.

Cock up your beaver,
And cock it fu' sprush,
We'll over the border
and gie them a brush;
There's somebody there
We'll teach better behaviour -
Hey, brave Johnnie lad,
Cock up your beaver!

Notes to the poem:

The second verse of this song is Burns's; The first is old. The New Century Dictionary from 1917 defines the following:

Cock, kok, n. The male of domestic fowl; the male of other birds; a vane; a person or thing having resemblance to a cock; a chiefman; a tap for drawing off liquids; the hammer of a gum; a small pile of hay; to set erect; to set on the head with an air of pertness; to draw back the cock of a gun;

Beaver, n. A rodent quadruped; beaver-fur, or a hat made of it; the face-guard of a helmet; a visor - a. Made of beaver, or of it's fur;

I'm not sure what this piece means, or it's context. It is probably good for a laugh at weddings. Comments welcome.