Brooklyn is going to pot!

The joke is that 420 is the weed number.

This weekend is April 20, one of the high holy days for marijuana consumption. Those who indulge in the increasingly-less-illegal (but still banned in New York) substance have a few options for entertaining themselves, aside from just, like, really looking at their hands, man.

On Friday night at 8 p.m., the cooler-than-thou Cooler Gallery (22 Waverly Ave. between Flushing and Park avenues in Fort Greene, thegreenroom.brownpapertickets.com) will host the Green Room Festival, an evening of plays perfect for those who might have an impaired attention span for some reason — the longest is only five minutes long! Each deals with the impact of cannabis on a different community, and a portion of the $15 ticket price will be donated to the New York Chapter of the National Organization for the Reform of Marijuana Laws. The show repeats on Saturday night.

On Saturday, celebrate the Green Day by going to a green space! The Soul Tribe Network plans to meet at the Prospect Park Carousel (enter on Flatbush Avenue at Empire Boulevard) at 11:11 a.m. on April 20, and then “let the universe lead the way,” as they roam Prospect Park and clean up trash, before heading to a smoke-friendly second location for an after-party.

In the evening, head to Coney Island for a celebration of the least accurate film ever made about marijuana use: “Reefer Madness!” This terrible propaganda film from the 1930s has been newly colorized, so you can mock the over-the-top acting while experiencing a full sensory overload. Tonight’s screening at Sideshows by the Seashore (1208 Surf Ave. at W. 12th St. in Coney Island, www.coneyisland.com) starts at 9 p.m., and your $15 ticket also includes a live performances from the band Pink Velvet Witch, and puppet appearance from Coney Island’s own Funny Face. No squares!

If this weekend of indulgence makes you want to cut back, buy a ticket now for next weekend’s special screening “Spoons, Toons, and Booze Says No to Drugs!” at the Nitehawk Cinema Prospect Park (188 Prospect Park West at 14th Street in Park Slope, nitehawkcinema.com/prospectpark). The brunch screening will feature a cereal bar, drink specials, and a screening of anti-drug cartoons from the 1980s and ’90s that are sure to scare you straight! The show will also include the government-sponsored “Cartoon All-Stars to the Rescue,” which aired only once in 1990 — but you can catch it twice, at 10:45 a.m. screenings on April 27 and 28. Tickets are $18.

Reach arts editor Bill Roundy at broundy@cnglocal.com or by calling (718) 260–4507.