I interviewed John Oates of Hall & Oates prior to their appearance at the Bumbershoot Festival in Seattle in 2012. Here's a few excerpts from that interview. 

Why lip-sync?

Daryl [Hall] and I both had singles out with our respective bands that were played on R&B radio in Philadelphia, and a radio DJ invited us to play a teenage dance. In those days, you would go out and lip-sync your record. We were waiting backstage in a really bad neighborhood in Philadelphia and a big gang fight broke out. We went down the service elevator, and that's how Daryl and I met.