Ican't believe that in 12 years no-one seems to have posted what the OP was originally after. "Maid Of The Mountain" is a totally different rugby song to "Mary Of The Mountain Glen". Can't remember much of it but it went something like this:

The maid of the mountain
She pissed like a fucking fountain
And the hairs on her dicky-di-do hung down to her knees
One black one, one white one
And one with a bit of shite on
The hairs on her dicky-di-do hung down to her knees

She married an Italian
With balls like a fucking stallion
And the hairs on her dicky-di-do hung down to her knees

....about all I can remember from the 1960s, when I last heard it, and as the OP said, it's pretty crude throughout.