Psychedelic experiences can be induced via breathing techniques. Look up holotropic breathing & pranayama..
Also when you don't sleep for a while, you'll start hallucinating. If you have a near death experience, you'll usually hallucinate. Everyone dreams. That by definition is hallucination, as some people's dreams blend into the 3d reality, resulting in cases of sleep paralysis, false awakenings & hypnagogic states. This blend between different realities is what's usually described as schizophrenia.
2 people can look at a table, one person sees nothing. The other sees a dancing cat with Justin Beiber's face in a tuxedo telling them to kill themselves..
Quite a few people have surrealist dreams which can be likened to these schizophrenic experiences. Only difference between ''normal people' and people with schizophrenia is that, one person's mind and senses can receive information from this other reality..
2 people can look at a tree and only one person would see it as what is commonly known as green AKA colorblindness. This is a clear indication of how relative everything is. There's no absolute. Just rigid relatives. Everything is just vibrations and electricity anyway..
Ingesting natural substances such as psilocybin mushrooms, peyota or ayahuasca is just another method of achieving a hallucinatory state..
It's in you. This technically makes you illegal..
By the way I'm doing LSD soon with a hot lady I met recently, who I'm trying to seduce. It is both our first times. Maybe it will be a first time for other things to happen..
Wish me blessings..