ASPEN - Anyone who wants to blow the whistle on life's daily injustices can do so at the Aspen Art Museum - from the back of a hippopotamus.The unique opportunity comes via the "HOPE HIPPO" installation, part of the Restless Empathy exhibit at the museum, which opened Thursday.The museum needs volunteers who are willing to perch on the hippo, read the day's news and blow a whistle each time they read something they perceive as an unfairness or social injustice."Obviously, that's a subjective thing. People blow the whistle for different things," said Jeff Murcko, public relations and marketing director at the museum.Artists Jennifer Allora and Guillermo Calzadilla created the first HOPE HIPPO for an exhibit in Venice, Italy, in 2005. They sent directions for creation of the life-sized Aspen hippo, which was constructed inside the museum gallery by locals using straw, mud and clay. The work is not meant to last - its ephemeral nature is much like the news itself."I'm kind of attached to it already," admitted Murcko, who will spend time on the hippo Friday."It's a chance to be part of art," he said.For Restless Empathy, the museum invited eight artists to create new projects or rethink existing bodies of work; each artist shares a capacity for creating and exploring empathy in unexpected ways, according to the exhibit literature.The exhibit runs through July 18, so there are plenty of slots available for hippo sitting. No one will be paid to sit there, though, explained Heidi Zuckerman Jacobson, museum director and chief curator. It's important to Allora and Calzadilla that participants be volunteers; payment would alter their perceptions of injustice, she said."If we don't have a volunteer ready to sit there, the hippo just sits there," she said.Zuckerman Jacobson will take a turn on the hippo this week, as well. Museum staffers who volunteer must make up their work at some other time, she said.In addition to its other aims, the HOPE HIPPO furthers the museum's goal of removing barriers to contemporary art, said Zuckerman Jacobson."How much more can barriers be removed than getting your clothes dirty sitting on a hippo?" she mused.(Actually, participants can sit on a small pad that makes the hippo more comfortable and keeps their clothes cleaner.)Volunteers may sign up for as little as an hour, or spend the day on the hippo. No food or drink is allowed up there, but sit-in relief is available for those who, for example, need a restroom break. Participants receive their own whistle to keep, and use again if they volunteer for more than one shift. They are instructed to deliver a short, sharp blast on the whistle, as their reactions to the day's news dictate.Aspen's local newspapers, the Denver Post and several nationally distributed newspapers are available to participants. A prize will be awarded to the individual who spends the most time on the hippo over the course of the exhibit, Murcko said.Anyone who's interested in signing up should call the museum at 925-8050 and ask for Luis Yllanes, registrar and manager of exhibitions.