'The term refers to the pact that Ulysses made with his men as they approached the Sirens. Ulysses wanted to hear the Sirens' song, although he knew that doing so would render him incapable of rational thought. He put wax in his men's ears so that they could not hear and had them tie him to the mast so that he could not jump into the sea. He ordered them not to change course under any circumstances, and to keep their swords upon him to attack him if he should break free of his bonds.
Upon hearing the Sirens' song, Ulysses was driven temporarily insane and struggled with all of his might to break free so that he might join the Sirens, which would have meant his death.'
When an individual takes Step Three, it is wise to enter into such a pact. What this means is that you are committing in advance to continuing, in perpetuity, to take every action suggested in the Big Book ('Alcoholics Anonymous') and by your sponsor regardless of how may feel or what you may think about such actions in the future. You are also authorising sponsors and friends to pull rank on you if you stray, supplant your perception of your situation and best interests with theirs, and direct your actions.
If you are an alcoholic of the variety described in the Big Book, there will be times when the Sirens call. They will call in your voice, and you will think it is your heart or at least you yourself that is talking to you. They will convince you that they are speaking in your best interest. The voices will suggest that you don't really want to stop drinking, or you don't need to, or you can have a break, or it won't work anyway, or it's too much effort. You will be incapable of rational thought.
If you have tied yourself to the mast and committed to the actions regardless of how you feel or what you think, you will be saved. The temporary insanity will lift, and you will wake up the next day, week, or month wondering how you could have been so foolish.
If you have reserved the right to adjust course based on your own thinking, good luck, because you may follow the sirens to your death.
With any luck, sufficient prayer will block your ears with sufficient wax to drown out the Siren calls entirely. But the pact will save you even if the Sirens call.