In Japanese, the word "chikan" refers to those who grope others in public or the unwanted touching itself. "AirDrop chikan" has entered the public discourse.
As this Japanese news broadcast points out, it's also called "cyber chikan".
In the West, the BBC reported on the "first cyber-flashing" in 2015 after a British woman was sent an unwelcome penis photo via AirDrop while travelling on a south London train.
Sadly, this was not an isolated incident. Twitter is filled with women (some men as well) recounting how random strangers have AirDropped unwelcome lewd photos.
Increasingly, the Japanese media has also been reporting on AirDrop chikan. Twitter users have been recounting the harassment for the past few years, advising others to set AirDrop to either "Receiving Off" or "Contacts Only".
— みっちゃん (@andlove326) October 14, 2018
"AirDrop chikan akan" (AirDrop痴漢あかん) or "Don't sexually harass via AirDrop".
According to Huffington Post Japan, there have been at least two "AirDrop chikan" arrests in Japan: One was in July in Hyogo Prefecture, with the suspect allegedly sending a lewd image while on a Kobe-bound train, and the other was in Osaka also earlier this year, with the suspect allegedly doing the same.
AirDrop chikan cases can be difficult to investigate. If the image isn't accepted, there isn't evidence for the authorities as the data isn't saved. The British Transport Police, however, recommend saving the image so the authorities have the data footprint necessary to mete out punishment.
As mentioned above, the way to avoid the possibility of unwanted images is set AirDrop to either "Receiving Off" or "Contacts Only".