Ahoy, matey! Best put down the grog while riding the Metro, or I’ll call you a bilge rat! Wait — sorry, I read my calendar wrong. Talk Like a Pirate Day was Wednesday. Today’s actually Park(ing) Day, an annual worldwide event dedicated to turning metered parking spaces into pop-up parks.

It got its start in San Francisco in 2005, when an art studio placed sod, a tree and a bench in a two-hour spot in a part of the city lacking public space. The concept has since been aped all over the world, using those familiar rectangles for a variety of unfamiliar purposes, including a bike repair shop and a wedding venue. The event’s goal is to get folks thinking about how urban space is allocated, and whether we really need as much asphalt as we have.

In D.C., which is growing rapidly while striving toward Mayor Gray’s goal that 75 percent of all trips in the city be car-free, these are issues that need to be pondered.

I suggest talking it out with friends over lunch Friday in the 1200 block of G Street NW. That’s where Casey Trees is setting up its installation, which will stretch across three parking spots. In addition to setting up sod, grass and (of course) trees, the nonprofit is inviting passersby to take a load off at a picnic table, chat with arborists and play a game of cornhole.

Hopefully, those who stop by will recognize not just the beauty of trees but also their environmental benefits, says Casey Trees’ Christopher Horn. And then they’ll be motivated to help the group reach its goal of increasing the city’s tree canopy from 35 percent to 40 percent by 2035. By their math, that requires planting 8,600 trees a year, while maintaining existing trees. The target: 216,300 trees in D.C. (Compare that to the 275,000 vehicles currently registered in D.C.)

Over in Rosslyn, instead of trees, you’ll see a shopping cart that’s nearly as big. The 7-foot-tall sculpture by J.P. Flick will be rolled into the space at the corner of Wilson Boulevard and Lynn Street, where people are invited to donate used clothing to the Arlington Street People’s Assistance Network.

Nearby, Artisphere (1101 Wilson Blvd., Artisphere.com) is hosting a free exhibit, “Beyond the Parking Lot: The Change and Re-Assessment of Our Modern Landscape,” to coincide with the event (it runs through Nov. 4). The exhibit, inspired by the Joni Mitchell lyric, “They paved paradise / Put up a parking lot,” showcases works that depict the decay caused by the rise of the automobile.

If you want to check it out after 5 p.m. or over the weekend, you’re in luck: There’s free parking.

Find out where every Park(ing) Day event is happening around the globe, donate to the cause and get pointers on how you can participate at Parkingday.org.

Walk Party: Whether you get around on Saturday by transit, walking, biking or teleporting, you’re taking part in Car-Free Day. Celebrate with other pedestrians at Feet in the Street at Fort Dupont Park, which will be closed to automobile traffic from 10 a.m. to 4 p.m. In its place? Fitness classes, garden tours and free bike rentals. Pledge your allegiance to the cause — even if you’re already car-free — at Carfreemetrodc.com for the chance to win an iPad, a bike and more.