The effects of the psilocybin shirt are often pleasant, even ecstatic, including a deep sense of connection to others, confusion, hilarity, and a general feeling of connection to nature and the universe.
Psilocybin is a naturally-occurring compound found in high concentrations in some species of Psilocybe and Panaeolus (collectively called "psilocybin mushrooms" or "psilocybian mushrooms"), and at low levels in a large number of species of the Agaricales. The spores of these mushrooms are completely free of both psilocybin and psilocin.
The total potency varies greatly between species and even between specimens of one species in the same batch. Younger, smaller mushrooms are relatively higher in alkaloids and have a milder taste than larger, mature mushrooms. Mature mycelium contains some amount of psilocybin, which can be extracted with an acidic solution, usually of citric acid or ascorbic acid (Vitamin C). Young mycelium (recently germinated from spores) does not contain appreciable amounts of alkaloids. Most species of hallucinogenic mushrooms also contain small amounts of the psilocybin analogs baeocystin and norbaeocystin.
Many types of psilocybin mushrooms bruise blue when handled or damaged - this is due to the oxidization of active compounds and is most notable in mushrooms with a high psilocin content. Several other non-psychoactive (and in some cases toxic) mushrooms also bruise blue.