Always assumed this is a young man talking to a young wife about an old husband - could be wishful thinking!
Jim Carroll

WAD YE DO THAT?
From Burns' Merry Muses of Caledonia

Gudewife, when your gudeman's frae hame
Might I but be sae bauld,
As come to your bed-chamber,
When winter nights are cauld;
As come to your bed-chamber,
When nights are cauld and wat
And lie in your gudeman's stead.
Wad ye do that?

Young man, an ye should be so kind.
When our gudeman's frae hame,
As come to my bed-chamber,
Where I am laid my lane;
And lie in our gudeman's stead_
I will tell you what,
He f-s me five times ilka night,
Wad ye do that?