It is pronounced shivaree and my Mom and dad had one when they married. I think it has passed out of tradition except perhaps in the depths of Louisiana. When newly weds spend their first night together a band of friends get together and when the lights go out, they begin a mock serenade with pots and pans and noise makers. Then the protocol is to invite them all in for refreshments. The more popular the couple, the more people attend. By the time of my first wedding in 1947, the custom had disappeared and was no longer a feature of country weddings. It is a quaint and charming old ritual and like so many others is lost in the past.