You think that's crazy, try being in the same house as a cat when you're tripping on psychedelics. They know when you've entered their realm, and the cheeky little bastards like to take advantage of that fact.

I had this one cat that was a normal cat when I was sober, but liked to pop in and out of existence whenever I was on 25i/2c-e/LSD/etc. This one time I hear him meowing from across the house; I turn towards the sound, and suddenly he's rubbing against my legs and purring. Reach down to pet him and he's gone. It was some seriously freaky shit.