It was narrated that 'Ali said:
"I felt too shy to ask the Messenger of Allah (ﷺ) about prostatic fluid because of Fatimah, so I told Al-Miqdad bin Al-Aswad to ask about it, and he (the Prophet (ﷺ)) said: 'Perform Wudu' for that.'" (RU)
English reference (RU): Vol. 1, Book 1, Hadith 157 (RU)
Arabic reference (RU): Book 1, Hadith 158 (RU)