What ingredient is banned from your kitchen?

I refuse to allow margarine in my home. I dislike the way it tastes and I don't like the results of anything it's added into. I will eat it if I am at someone else's home to not be rude, but for me, I refuse to buy it.

Edit: I use the word banned loosely. Don't take the term here literally please. I personally won't buy it, but if someone wanted me to cook with it, I would.