An estimated 10,000 people gathered in London's Hyde Park on Monday in honor of 4/20, the annual pro-pot rally/celebration. Well it didn't take long for the 5-0 to arrive and totally harsh peoples' mellows. 

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Apparently the marijuana smoke could be smelled up to a half mile away. Police arrived on the scene and arrested more than 50 people who failed to comply with the event's strict 5 p.m. curfew. They were taken into custody on various drug-related offenses. 

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Weed is still illegal in the U.K., of course, but that didn't stop these cannabis enthusiasts from sparking up for the cause. It also didn't keep police from stopping people to check for drugs on their way to the event. Bummer dudes.