Tenacious D in the Pick of Destiny

To become the greatest band of all time, two slacker, wannabe-rockers set out on a quest to steal a legendary guitar pick that gives its holders incredible guitar skills, from a maximum security Rock and Roll museum.
In Venice Beach, naive Midwesterner JB bonds with local slacker KG and they form the rock band Tenacious D. Setting out to become the world's greatest band is no easy feat, so they set out to steal what could be the answer to their prayers... a magical guitar pick housed in a rock-and-roll museum some 300 miles away.