Julianne Hough deeply regrets her ill-advised 2013 Halloween costume, in which she donned blackface while dressed as Suzanne "Crazy Eyes" Warren (Uzo Aduba) from Orange Is the New Black.

Hough apologized for the costume back in 2013, but issued another mea culpa in a recent interview with Allure magazine.

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"Ignorance is sometimes not bliss," the Dancing With the Stars judge tells Allure. "I really had no idea what I was doing, and it was all out of fun and respect for the character. I don't even know how to talk about it because it's such a sensitive topic. It makes me so sad to think that I was that dumb. I learned a big lesson."

Hough, 26, drew fire from stars and non-celebrities alike when photos of her in the costume surfaced online two years ago. Aduba called the costume choice "unfortunate," but encouraged people to move on in the wake of Hough's initial apology.

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