According to Jim Recap: Cheryl Sings
As Cheryl tries to keep up with her cousin Mindy, she makes one of the most boneheaded claims of all - she says that she sings for the band. It's not bad enough to simply claim that she cans sing, but she says she sings for the band. Unfortunately, Mindy calls her on it, because she's having an engagement party the next week, and she needs a band - so of course she would ask her own cousin to sing. This isn't going to be pretty.
Jim, or course, isn't helping. He's all to eager to let Cheryl make a fool out of herself for trying to outdo her cousin. At least, he is right up until he hears that Mindy's soon-to-be husband is a record producer for a blues company, at which point he wants the band to look great, just in case they might get a record deal out of the gig. Then they have to decide who will tell Cheryl that she stinks.
Since he's married to her, Jim gets the honors, so on the way to the party, he fills her in. She's hurt, but understands. So as Jim and the band get up on stage to sing their song, and introduce it to the record producer that's about to get married, something strange happens - Mindy's husband-to-be announces that he isn't a producer. He works for the company all right, but he's an accountant.
And with that, Cheryl decides that she will sing after all. So she joins the band for a rocking rendition of Proud Mary. Way to go, Cheryl!
