Crown Stupefiers are substances that, when ingested into the body, interfere with, block, or otherwise distort the subtle (and not so subtle) operations of the Crown Chakra. Crown stupifiers are dangerous and prevent full activation of the crown chakra. Stupifiers should be avoided like the plague that they are.
Crown stupifiers include substances like alcohol, pharmaceuticals (psychoactive or otherwise), neurotoxins, and any other chemicals which interfere with the physiological, cellular, neural, or quantum operations of the brain. This includes, it should be noted, the slew of chemicals that you find in processed foods.
Contrast crown stupifiers with Connection Supplements
It is also important to note that brain operations can be very subtle and even current technologies like the MRI (Magnetic Resonance Imaging) are insufficiently sensitive to document the range of physical and quantum operations carried out in the brain. Therefore, just because an effect is not observed in the short term does not mean an effect (which may be cumulative and damaging over the long term) is not present.
Crown stupefiers are not confined to substances. The school system, which its overemphasis on the development of left brain modules and skills, television, and other forms of media that discourage critical thinking and interfere with the development of balanced brain functions, can also be considered crown stupifiers. In addition, a pathological socialization process, abusive parenting, and negative emotional experiences can contribute to crown stupefaction through the suppression of crown chakra energies.
The identification and elimination of substances, institutions, and practices which discourage proper development of the Crown Chakra, or encourage suboptimal or dysfunctional operation, should be a primary concern for all those individuals interested in assisting individuals to realize the potential of a fully connected Physical Unit.
Harold Johson provides a fascinating and highly recommended look at the destructive power of alcohol
Sharp, Michael (BOOK3). Lightning Path Workbook Three: Connection. Lightning Path Press. 
- Johnson, Harold R. Firewater: How Alcohol Is Killing My People (and Yours). U of R Press, 2016. https://amzn.to/2D142T4.