A newly uncovered secret in Los Santos has players again clawing through Grand Theft Auto V, hoping to discover even more hidden Easter Egg weirdness.

The “Black Cellphones” secret was discovered by Twitter user KarmaIngram1, according to Kotaku’s report, and the full breadth of it is not yet known. It’s a phone number you type into your GTA V character’s in-game cellphone—doing so triggers an explosion, and changes the phone the character is using into a black-colored variant. And that’s … it. So far.

But of course, players think there’s more to the story, and there’s a whole subreddit currently on the case, trying to figure out if there’s more to the Black Cellphones cheat. The video above, from YouTuber NoughtPointFour, runs down the information discovered so far and speculates on the mystery, suggesting the name is referencing the idea of “black,” or untraceable, phones that can be used for illegal activity and to access websites or call numbers players couldn’t previously utilize.

GTA V has been full of secrets, but seemed like players had pretty much exhausted it until this new addition. It might be that Rockstar has patched in some new mysteries, as they did by adding Bigfoot to the game last September. Either way, players are back on the case like a fleet of Sherlock Holmeses, if Holmes drove a car and ran over 50 pedestrians on his way to solving every mystery.