It doesn’t matter if you’re walking through your neighborhood or at the beach on vacation — the “Trashtag Challenge” can be done anywhere, at any time. The challenge is simple: Armed with garbage bags, people choose a spot and get to work picking up litter from the area. Once they’re done, they upload before-and-after photos on social media, using the hashtag #trashtag. Over the weekend, the challenge went viral, with users from around the world showing the massive amounts of trash they cleaned up from parks, beaches, hiking trails, roads, and schools. Some said they did it as part of their birthday celebrations, others while they were on road trips or just looking for something to do. The first challenge took place in 2015, BuzzFeed News reports when a lighting company created the hashtag to remind people about the importance of picking up trash while spending time outdoors.