Why don’t they teach these things in schools? LOL.
A koro epidemic struck Singapore in October 1967 for about ten days. Newspapers initially reported that some people developed koro after eating the meat of pigs inoculated with anti-swine-flu vaccine. Rumours relating eating pork and koro spread after a further report of an inoculated pig dying from penile retraction. The cases reported amounted to 97 in a single hospital unit within one day, at five days after the original news report. Government and medical officials alleviated the outbreak only by public announcements over television and in the newspapers.
FYI I chanced upon this gem while reading the Wikipedia entry on “running amok”.
You can read more about the koro epidemic here (downloadable PDF file).