Below is the song, Peggy Ramsey, as it appears in Pills to Purge Melancholy, 1719-20. I'd like to know from a Scots speaker what this means, please. I'm more or less fine with the first three verses (except what is a Wethergig?), then after that I get completely lost. It's supposed to be a humorous saucy song, but I'm afraid it's lost on me! Even if you can only translate bits into English English, I'd be grateful for the help.

PEGGY RAMSEY

BONNY Peggy Ramsey that any Man may see,
And bonny was her Face, with a fair freckel'd Eye,
Neat is her Body made, and she hath good Skill,
And square is her Wethergig made like a Mill:
With a hey trolodel, hey trolodel, hey trolodel lill,
Bonny Peggy Ramsey she gives weel her Mill.

Peggy to the Mill is gone to grind a Bowl of Mault,
The Mill it wanted Water, and was not that a fault;
Up she pull'd her Petticoats and piss'd into the Dam,
For six Days and seven Nights she made the Mill to gang;
With a hey, &c.

Some call her Peggy, and some call her Jean,
But some calls her Midsummer, but they all are mista'en;
For Peggy is a bonny Lass, and grinds well her Mill,
For she will be Occupied when others they lay still:
With a hey, &c.

Peg, thee and Ise grin a poke, and we to War will leanes,
Ise lay thee flat upon thy Back and then lay to the steanes;
Ise make hopper titter totter, haud the Mouth as still,
When twa sit, and eane stand, merrily grind the Mill:
With a hey, &c.

Up goes the Clap, and in goes the Corn,
Betwixt twa rough steans Peggy not to learn;
With a Dam full of Water that she holdeth still,
To pour upon the Clap for burning of the Mill:
With a hey, &c.

Up she pull'd the Dam sure and let the Water in,
The Wheel went about, and the Mill began to grind:
The spindle it was hardy, and the steanes were they well pickt,
And the Meal fell in the Mill Trough, and ye may all come lick:
With a hey trolodel, hey trolodel, hey trolodel lill,
Bonny Peggy Ramsey she gives weel her Mill.