I have to laugh about them making this out to be a teen thing. Messing with people who have insecure settings is a cornerstone of hacker culture. I'd do this all the time if I had an iPhone. I haven't been a teen for 20 years.
Phones these days aren't visible by default so it's rarely possibly anymore.
A usual citing on my network list was "Yell Penis for Password".
I've also had people, more deviously change their network name to "Galaxy Note 7" while in the airport or in-flight to stir frenzy after they were banned at airports.
I used to attempt Bluetooth pairing around the office with my phone set to "TURN OFF YOUR DAMN BLUETOOTH". The number of visible devices did decrease after a while!
In the early days of coffee-shop wifi, I used to browse around Network Neighborhood looking for people's shared MP3 folders. If they had stuff I liked, and their share was writable, I'd leave 'em something in return, along with a little thanks.txt :)
I wonder what reaction you'd get making your ESSID a penis 饟偢
https://boingboing.net/2018/10/31/can-you-see-the-penis-char...
It was harmless fun sending funny memes back and forth with strangers who were all trapped in an airline terminal. The hardest part was trying to keep a straight face when you saw some teenagers reaction when you sent them a sloth meme about leaving their airdrop open.
I would find random shares open on people's machines, then fill their entire hard drive with cat pictures. I usually left a few GB so they could save documents or whatever because I wasn't that much of an asshole.