One of the new features added to Los Santos in the next-gen release of GTA V is peyote! Using the cactus will cause your character to totally trip balls and have an out-of-body-experience, following in the footsteps of millions of teenage Californians. There's 27 peyote locations, but the animal you get to play as is randomized:
You can even play as an adorable cat- oh god no!
It's important to note that this is an official feature, not a mod (like this one that made the rounds earlier this year).