The spelling of the acronym "WDF" is quite straightforward. It consists of three letters: the letter W, the letter D, and the letter F. The pronunciation of this word can be transcribed using the International Phonetic Alphabet as /ˈdʌbəlju di ˈef/. It is often used in informal online communication and stands for "What da f***." This expression is used to express surprise, confusion, or disbelief at something someone has said or done.