Amid the well-known asceticism and rituals of Rabbi Isaac Luria, better known as the Ari, and his followers – like the Kabbalat Shabbat prayers all Jewish denominations say every Friday afternoon – are some lesser-known segulot and tikkunim (signs/amulets and spiritual repairs). And some of those appear to violate the accepted halakha – like, for example, the Holy Blow Job.
Rabbi Isaac Luria, better known as the Ari, would be by today's secular standards a mentally ill cult leader. But by pre-modern standards, Luria was a holy man, and the entire hasidic world along with almost every Serfardi community worship him (almost literally so), as do some non-hasidic Ashkenazi haredim. Amid the well-known asceticism and rituals of the Ari and his followers – like the Kabbalat Shabbat prayers all Jewish denominations say every Friday afternoon – are some lesser-known segulot and tikkunim (signs/amulets and spiritual repairs). And some of those violate halakha, like, for example, the Holy Blow Job:
ושני בנים יש לה בבטנה ויש לה תיקון אם ימצא. א"ל [אמרו לו, לאר"י] יגיד לנו מר. אמר להם התיקון הוא שיבא איש שלא ראה טיפת קרי מימיו ויתן בריתו בפיה ומיד תלד ותינצל. א"ל מי זה האיש ונלך אליו. א"ל יודע אני ואין לי רשות לגלותו שלא להוציא לעז על אחרים. אבל זאת עשו והוציאו כרוז בכל העיר מי האיש אשר יודע בעצמו שלא ראה טיפת קרי בימיו, יבא ויציל ג' נפשות מישראל [את האישה המתקשה ללדת ואת התאומים שבבטנה]. כן עשו. וכששמע הגאון מוהר"ם [מורנו הרב משה] גאלנטי הזקן, מיד קם ובא עמהם ונתן בריתו בפיה ומיד ילדה. (ספר תולדות האר"י, מהדיר מאיר בניהו, מכון בן צבי, עמ' 224-225)
Dr. Tomer Persico, an academic scholar of religion at several Israeli universities, has a long post in Hebrew (from which the above quote is taken) on the Holy Blow Job and other similar segulot and tikkunim which you can read here.
To paraphrase the above Hebrew quote, a woman in Sefat approximately 440 years ago was having a difficult pregnancy and a prolonged labor and it was feared she would die. People rushed to the Luria for advice and a blessing. He said a man who had never spilled even a drop of semen in vain (i.e. had his entire life only ejaculated, even just a drop, inside his wife's vagina). There is such a man, the Ari said, but I cannot reveal who he is. But if you can find him, have him place his penis in the woman's mouth and put his semen on in it (on her lips or caused by her lips). And that will heal her. So posters were put up around Sefat and the surrounding villages asking that such a man come forward and save the life of a Jewish woman. And who answered the call? Rabbi Moshe Galanti (d. 1608) a leading disciple of the author of the Shulkhan Arukh, Rabbi Yosef Karo. Karo himself had a years long conversation with a disembodied spirit and exhibited other classic signs of mental illness.