The 74-year-old Duterte spoke at a campaign rally in Puerto Princesa City for the nation's May mid-term elections; he touched upon a wide range of topics, from foreign affairs to the economy to human anatomy.
"If God gave me a small penis, I would have cut it off in front of the altar," Duterte said, making the audience burst into laughter. "Son of a b***h, is this all you have given me?"
He also recalled his days at the Young Men's Christian Association (YMCA) in Manila. He said he would not care much about dressing himself in the dorm, much to the amusement of other residents.
"My towel, I wouldn't (wrap it around me). I'd just walk towards them (naked); they would admire me. (They'd tell me) ‘Son of a b***h, Duterte, you're so hard!'"
He went on to detail how his member would "almost look up to the sky" when he was young — all thanks to positive genetic influences.
"I'm very thankful to my father," the president said. "At least he let me out into the world highly-equipped."
He added how his equipment would at times do him a disservice when he entered a place filled with women. "They ran away. 'We don't like him. That skinny guy. He won't stop (having sex)'."
The outspoken 71-year-old politician took office at 71 years of age in June 2016 after a three-year stint as the mayor of Davao City, the country's third-largest.
The president has earned a reputation for his vociferous opposition to narcotics. He has launched a war on drugs; authorities estimate he has killed over 5,000 people, which has led to a domestic and international backlash.
Duterte, a baptised Catholic, is known to have used strong language against the Catholic Church and its parishioners. He commonly makes rape jokes and has called former US President Obama a ‘son of a whore'.