If I'm Dyin' I'm Lyin' - S2-E9
Revealing mistake: When one of the Gumbels is holding a pencil in his mouth and nodding repeatedly, the shaft of the pencil moves with his mouth, but the tip of the pencil (protruding from his hand) stays still. (00:17:35)
Chosen answer: It's a real song called "Elvira". Originally by Dallas Fraizer in '66, however, this version seems to be the Oak Ridge Boys cover version. However, the mega lesbians skip the verse and just sing the chorus after the opening line.
Bishop73