"Something about her Ladyship’s soap."
In Season 2 Thomas suggests to O’Brien that Her Ladyship plans to find a replacement for the lady’s maid. Believing her career to be at stake, O’Brien foolishly lashes out at the pregnant Lady Cora, deliberately moving a piece of dropped soap from under the tub for Lady Cora to slip on and lying about it. Just as O’Brien second guesses her action, Lady Cora exits the tub and falls badly, causing her to lose the little boy that she was carrying.
OMG THE FUCKING SOAP
I FORGOT ABOUT THE SOAP