No, the idea isn't to be as annoying as Link's fairy friend, but rather to draw your attention.
"People think it's just an app that says 'Yo'. But it's really not," Or Arbel, who created then coded the app in just eight hours, told the New York Times. "We like to call it context-based messaging. You understand by the context what is being said."
How it works is simplicity itself. You have a list of contacts. You tap one of those contacts, and they receive a notification saying simply, "Yo", along with an audio alert of the word being spoken. According to the app's description, it can mean pretty much whatever the sender wants it to mean, depending on context:
Wanna say "good morning"? just Yo.
Wanna say "Baby I'm thinking about you"? -- Yo.
"I've finished my meeting, come by my office" -- Yo.
"Are you up?" -- Yo.
The app has received $1 million in angel funding from a group of investors led by Moshe Hogeg, CEO of image-sharing app Mobli, who inadvertently commissioned the app: he asked Arbel to design a single-button app that he could use to call his assistant without having to pick up the phone. According to the Financial Times, Arbel didn't have time at that point -- but recalled it a day later after having simplified conversations with friends on WhatsApp.
At first glance, it may seem pretty silly, but the app's use during the FIFA World Cup highlights its potential: users can send a single "yo" to the username "worldcup" to receive a yo in return anytime a team scores a goal. At the moment, this involves a human watching the game and manually sending the alerts, but that won't always be the case.
Arbel's ideas, according to the newly launched API, for where the app could go next include a button for bloggers to send followers a yo whenever they post an update. Or perhaps a favourite online retailer could send out a round of yos whenever they launch new stock.
Even in its current form, the app is collecting significant attention, both positive and negative, with over 50,000 downloads and more than 4 million yos sent.