Bicycle Day

Bicycle Day is the informal anniversary, observed annually on 19 April, of Swiss chemist Albert Hofmann's first deliberate self-experiment with LSD-25 in 1943. Working at Sandoz Laboratories in Basel, Hofmann took 250 micrograms of the compound he had synthesised five years earlier and -- with wartime restrictions on motor transport in force -- cycled home with his lab assistant as the effects came on, producing the world's first intentional LSD trip. The day has since become a touchstone for the worldwide psychedelic-research and counterculture communities (Wikipedia)