The Last of Us has been burning up the best-selling software charts since its launch in June, but the game is even hotter than we thought: A pair of phone lines appearing on a sign in the game appear to be actual phone sex hotlines.

Kotaku first discovered that the numbers, which appeared on a sign in the game, were working ones. Naughty Dog, the (perhaps appropriately named) developer of the game, said the numbers were an accidental inclusion.

“That was an artist’s mistake,” the game’s creative director Neil Druckmann told Kotaku. “We’re now working to take it out. It was just an honest mistake.”

A Sony spokesperson said: “We included some random phone numbers in the game starting with 555, which is a common practice in North American television shows, films and video games, as they are fictitious numbers. It has come to light that for certain 555 phone numbers that begin with an 800 area code, the same does not apply, so a patch was created to address this issue. The patch was deployed today in North America, Latin America, Europe and Asia, and will be deployed shortly in Japan.”

The Last of Us is an M-rated game, so it’s not as if young children will be seeing these numbers. Still, it’s an embarrassing PR problem for Sony while the company is gearing up to launch the PlayStation 4 this fall. Sony’s quick work patching the game will minimize any damage, and it’s unlikely to have any impact on sales.

Source: CNBC