hopping down the bunny trail
To be so heavily under the influence of a psychedelic or dissociative substance that you are unable to distinguish normal reality from the magical reality that has taken hold of your mind. Seeing pixelated kaleidoscopic patterns in the carpet, being afraid to open the freezer because you're afraid that the fishsticks will attack you, and the ability to talk to squirrels are some sure signs that you're hopping down the bunny trail.
That PCP I had last week really had me hopping down the bunny trail.