Some 17.6 million people have signed up to a game which visualises the words they use most often in Facebook posts.
But privacy experts have claimed all these hapless social media lovers may have inadvertently handed all their private information to advertisers.
According to mirror UK- Anyone who used a wildly popular Facebook app created by a firm called VonVon have "agreed to give up almost every private detail about themselves to a company they likely know nothing about", analysts from consumer tech group Comparitech suggested.
Whenever you sign up and ask VonVon to collect your "most used" words, it asks for access for private details including your name, age, profile pictures, Facebook friends and any other "public information" you have given the social network.
This information can be stored on VonVon servers around the world and could even be given to advertisers.
"We’ve singled out Vonvon because it recently went viral, but it’s far from the only data dealer to masquerade behind a viral quiz mill," said Comparitech's Paul Bischoff.
"Facebook is a haven for a large number of these companies and, frankly, hasn’t done enough to educate or warn users about the risks."
He advised concerned social media users to avoid using Facebook quizzes, unless they do not require authentication - which means logging into your account.
On the social network, users are now advising each other to steer clear of the most-used words app.
"Get paranoid for one moment," wrote one woman.
"Think for a moment who you most don't want to have all your info, and that of your friends.
Another raged: "People, stop playing random cool-looking quizzes from companies you don't know - especially those that ask you for a bunch of information access things to let you play, in return for a prettily designed but totally useless infographic."