Magnificent, Yep
Mom was ecstatic about her child’s excellent chemistry grade. So much so that she cursed about it unintentionally! In her defense, she had no understanding what WTF meant in the first place. It nearly appears as if she doubts her child’s or daughter’s talents.
Mom simply mistook the popular online term for “Wow, That’s Fantastic.” It appears that no one bothered to correct her, which could lead to more amusing material in the future.