About once per decade, the medical profession takes a careful look back at Thailand’s plethora of penile amputations. The first great reckoning appeared in a 1983 issue of the American Journal of Surgery. Surgical Management of an Epidemic of Penile Amputations in Siam, by Kasian Bhanganada and four fellow physicians at Siriraj Hospital in Bangkok, introduces the subject: It became fashionable in the decade after 1970 for the humiliated Thai wife to wait until her [philandering] husband fell asleep so that she could quickly sever his penis with a kitchen knife. A traditional Thai home is elevated on pilings and the windows are open to allow for ventilation. The area under the house is the home of the family pigs, chickens, and ducks. Thus, it is quite usual that an amputated penis is tossed out of an open window, where it may be captured by a duck.
The report explains, for readers in other countries: The Thai saying, ‘I better get home or the ducks will have something to eat,’ is therefore a common joke and immediately understood at all levels of society
— via redwolf.newsvine.com