Skip to main content
Dictionary
Store
Blog
World
Help
Advertise
Chat
System Status
Information Collection Notice
Trademark Concerns
reCAPTCHA Privacy
Terms of Service
reCAPTCHA Terms
Privacy Policy
Accessibility
Report a Bug
Data Request
Contact Us
Security
DMCA
© 1999–2026 Urban Dictionary ®
Mugs
Tees
Hoodies
Pro Customization
Create unique products with your own words and definitions
Preview
Personalize Your Design
Your Word
Your Definition
Bicycle Day is April 16, commemorating April 16, 1943, when Dr. Albert Hofmann first took LSD intentionally. Three days earlier, he had absorbed a small amount of the drug either through his fingertips or by accidentally ingesting it. On Bicycle Day, he took 250 µg of LSD intentionally and, fearing he had made himself ill, cycled home from his lab. During his bicycle ride, he experienced the effects of LSD, making this the date of the first ever acid trip. He wrote about his experiments and experience on April 22, which was later put into his book LSD: My Problem Child. This day (for LSD users) is when they celebrate the discovery and first ever use of the drug.
Text fits
Save
Cancel