Stuck inside these phone bones

The story:

I was in the car with my boyfriend (now husband) when this song came on the radio. I said the lyrics, and my husband, who sang in a band for years, looked at me incredulously and said, "WHAT did you just say?" When I sang it again, he just started laughing hysterically. Oh, and I just found out this song is by Paul McCartney, NOT Chicago, like I had thought.