The rumor mill that feeds GTA 5 players with theories around upcoming (or unfortunately cut) content rarely yields anything legitimate. However, the game's PC port has made data mining much easier, and the existence of the famed Bigfoot in the game is one of the few rumors that ended up being true.
One of the weirder features of GTA 5 are the psychedelic Peyote Plants which, upon discovery and ingestion, will turn the player character into an animal temporarily. They are fun little easter eggs that can provide a bit of diversion, but all were swiftly discovered after release — all but one, it seems.
The Grand Theft Auto franchise has a bit of a history with the Bigfoot, or Sasquatch. Back in the San Andreas days the internet landscape was very different, as was the community. Rumors swirled back then too, but the false ones weren't as loudly discredited. One particular rumor, that a Bigfoot NPC could be found at very specific times, in very specific places, lived on. Modding allowed players to fake sightings, but eventually, it became clear that the rumor is a hoax.
With GTA 5 returning to the setting of San Andreas, it makes sense that Rockstar would homage one of the biggest urban legends of the older title with something tangible this time around. Digging in the game files revealed that there was indeed a Sasquatch peyote somewhere in the game, and even more digging turned up the instructions on how to find it.
Initially, the code included references to a trio of undiscovered peyotes. These were eventually added in the Freemode Events update, but one remained to be found — until the data miners discovered a snippet referring to PEYOTE_ATTRACT_SASQUATCH. If that isn't a smoking gun, nothing is.
This is a highly obscure easter egg, as the method of accessing it is so extremely specific that the chances of anyone happening on it accidentally or organically were astronomical. Since nobody found the plant on their own after the discovery of the file, the veracity of the rumor was called into question — until finally someone confirmed it.
