JAR meaning in Community ?

"J.A.R." is a song by the American rock band Green Day. The song was a previously unreleased track from the Dookie sessions but it was later featured on the soundtrack to the movie Angus in 1995. The acronym stands for 'Jason Andrew Relva', a childhood friend of Green Day bassist Mike Dirnt. Jason Relva was born on November 16, 1972 and died at the age of 19 on April 18, 1992 as the result of injuries sustained from a car accident. Mike Dirnt wrote the song in remembrance of him.In August 1995, the song reached number one on the Billboard Modern Rock Tracks chart and spent 16 weeks on it. This song was worked on during the Dookie demo, but later removed on final track. The song peaked at number 22 on the Hot 100 Airplay chart.

The song was also featured as the eighth track on Green Day's 2001 greatest hits collection International Superhits!, and on their 2011 live album Awesome as Fuck.

Jason Relva is thanked in the liner notes of 1,039/Smoothed Out Slappy Hours and Kerplunk.