Read: A Brief History of Embarrassing Attempts to Get the Youth to VoteAvengers director Joss Whedon corralled a bunch of famous celebrities into one room to shamelessly remind viewers to register to vote—and try to encourage people not to vote for Trump, while they're at it.In the PSA, the all-star cast—including Julianne Moore, Robert Downey Jr., Scarlett Johansson, and Neil Patrick Harris, among others—say, "You only get this many famous people together if the issue is one that truly matters to all of us." An issue like, for example, "a racist, abusive coward who could permanently damage the fabric of our society," Don Cheadle adds.And if that didn't convince you, a silver-haired Mark Ruffalo gets roped into saying he'll do a nude scene in his next movie, should you cast a vote for anyone other than Trump. Even Martin Sheen, who played everyone's favorite TV president Jed Bartlet on TheWest Wing, makes a rousing appearance.Although the PSA is more anti-Trump than pro-Hillary, a bunch of other former West Wing cast members will be campaigning for the Democrat in Ohio this weekend, according to a Clinton aide.While it's always entertaining to see the embarrassing ways that celebrities get involved in every election cycle, it's a wonder they even needed to make an anti-Trump PSA at this point, now that all of his Twitter outbursts have been collected into an easily searchable online database.Read: A Brief History of Embarrassing Attempts to Get the Youth to Vote