Here's that band Fall Out Boy's performance on Conan last night, which was a half-baked homage to Spinal Tap, complete with an appearance by Harry Shearer. It's basically just Fall Out Boy going about a usual performance while Spinal Tap stuff happens in the background.
Here's an interview with Fall Out Boy and Harry Shearer for Conan's website. I swear it's the last Fall Out Boy interview I'll ever post here unless Louis C.K. like becomes their drummer or something: