An Americanism, used largely in the Southeast but generally understood if used in other regions. One is "in" a swivet, and the operative verb is "get," as in "don't get yourself into a swivet" -- or if already gotten, "she is in a swivet." Like many dialect words, the origin is unknown, but it first appeared in print in 1892. I sometimes, growing up, would use it as a verb, but that always got me a funny look. But then, some people don't like it when you verb things.
Oh wouldn't you know it, but that man actually showed up, and now my son's got his dander up and the bride's in a swivet.