Chickenfoot swung on by 'Jimmy Kimmel Live!' on Thursday night to rock out two songs -- 'Big Foot' and 'Three and a Half Letters' -- from their recently released second album, 'III."

During the main segment of the show, Sammy Hagar and the boys tore through 'Three and a Half Letters (I Need a Job),' a song that recently inspired the band to dedicated a section of their website for fans to share letters detailing their search for work and other problems they are facing in this tough economy. During the performance, Hagar actually read from what looked to be letters from fans scrawled in big black marker.

After 'Letters,' Chickenfoot then "play[ed] us off the air," as Kimmel said, with the upbeat scorcher 'Big Foot' going as the credits rolled. That tune, with its automobile-inspired lyrics like "I'm gonna drive all night ... I got both hands on the wheel, and my big foot on the gas yeah," recently landed on Ultimate Classic Rock's tally of the Top 10 Sammy Hagar Driving Songs.

Hager, who turned 64 last month, celebrated the birthday with -- of course -- a multiple-day bash at his Cabo Wabo Cantina in Cabo San Lucas, Mexico. The big shock for fans, however, was the surprise appearance of Chickenfoot themselves at one of the parties.

Chickenfoot are in the middle of a brief U.S. trek dubbed the Road Test Shows that hits St. Louis tonight (Nov. 4) and is scheduled through a Tuesday gig in New York. We're gonna be in Chicago, look for a full report soon.

Watch Chickenfoot Perform 'Three and a Half Letters' on 'Jimmy Kimmel Live!'