Philippine President Rodrigo Duterte called Barack Obama a "son of a whore" on Monday as he vowed not to be lectured by the US leader on human rights when they meet in Laos..... The acid-tongued Duterte bristled at warnings he would face questioning by the US president over a war against drugs in the Philippines...... ........"You must be respectful...... "You must be respectful......Son of a whore, I will curse you in that forum," Duterte told a news conference shortly before flying to Laos to attend a summit....."