It’s hard to believe that “The Big Lebowski,” a film that follows a slacker/stoner/bowler as he seeks justice after someone pisses on his rug, has spawned its own festival. And it’s also hard to believe that said festival has been going on for 15 years! But hey man, The Dude abides. So come celebrate with your fellow achievers Friday with a movie party that includes live music by Black Bear Combo and an outdoor screening of “The Big Lebowski.” And on Saturday enjoy a bowling party with a costume contest, trivia, unlimited bowling and Lebowski-themed games and what-have-you.