-Racist comments like:
"Shall I tell you the law of God in regard to the African race? If the white man who belongs to the chosen seed mixes his blood with the seed of Cain, the penalty, under the law of God, is death on the spot. This will always be so." (Journal of Discourses, vol. 10, p. 110).
-Weird things he taught as doctrine such as Blood Atonement (it basically means there are certain sins that are large enough that Christ's blood can't pay for them, and you have to pay for it...with your own blood).
"There is not a man or woman, who violates the covenants made with their God, that will not be required to pay the debt. The blood of Christ will never wipe that out, your own blood must atone for it . . . " (Journal of Discourses, vol. 3, p. 247; see also, vol. 4, p. 53-54, 219-220).
Those are probably the most famous BY's whaky statements.