'Teach your sons:' Kourtney Kardashian talks Menstrual Hygiene Day in bikini pic - USA TODAY

'Teach your sons:' Kourtney Kardashian talks Menstrual Hygiene Day in bikini pic  USA TODAY

The "Keeping Up With the Kardashians" star shared a sexy swimsuit pic and urged mothers to talk to their sons about periods on Menstrual Hygiene Day.