April 20 has long been notorious as a marijuana counterculture holiday, and about 100 University of Minnesota students celebrated the occasion Tuesday with a public smoke session on Northrop Mall. The students gathered on the mall, and at exactly 4:20 p.m., dozens lit and shared marijuana cigarettes and hookah tobacco, and played instrumental music. No police intervention was present. University police Chief Greg Hestness said he wasnâÄôt aware of the dayâÄôs significance. âÄúI think that flew under our radar here [at the University police department],âÄù he said. âÄúI donâÄôt know exactly what weâÄôd do about it anyway, unless it was a public event.âÄù When told that the event was in fact public, Hestness said University police did not respond because the department received no calls of complaint. The UniversityâÄôs gathering paled in comparison to the annual celebration at the University of Colorado at Boulder, where 10,000 people met on campus to smoke marijuana on April 20, 2009. The University of California Santa Cruz is also notorious for its gathering: Campus police restrict visitor and vehicle access during the smoke-out. As for the University, Hestness said the UMPD will not alter its actions for April 20, 2011. The staff does not have the sufficient staff to âÄúset up a stingâÄù or surveillance detail in anticipation. Environmental and ecological engineering junior Zach Tauer, president of Students for Sensible Drug Policy, said most students came to the smoke-out between 4 p.m. and 5 p.m. Tauer said he smoked hookah and cigarettes Tuesday but not marijuana. Attendees played various instruments and chatted, while passers-by gawked at smokersâÄô boldness. For many marijuana smokers, 4/20 is believed to be a police code for smoking the drug. However, Steve Hager, former editor of High Times, a New York-based magazine that covers marijuana, has a different story for the origin of 4/20. He says the ritual is connected to a group of California teenagers who smoked marijuana every day at 4:20 p.m. in the 1970s. The story about the teenagers eventually spread and turned into an annual event in places around the country.