Three Ugly Stepsisters = Three Cysty Step Uglers.
The Weird Sisters as in the three witches in MacBeth. To me those three BODs are like evil witches.
Double, double toil and trouble;
Fire burn and caldron bubble.
Fillet of a fenny snake,
In the caldron boil and bake;
Eye of newt and toe of frog,
Wool of bat and tongue of dog,
Adder’s fork and blind-worm’s sting,
Lizard’s leg and howlet’s wing,
For a charm of powerful trouble,
Like a hell-broth boil and bubble.
Double, double toil and trouble;
Fire burn and caldron bubble.
Cool it with a baboon’s blood,
Then the charm is firm and good.
The whole incantation:
http://www.potw.org/archive/potw283.html