It was funny a few years ago, when I had to grade students answering a quiz about web services. There was a question about which components were necessary for a valid GET request. The required answer was a list of 4-5 components, such as the "GET" verb, the URI, the HTTP version, etc.

And it was rather controversial that some listed a body as necessary for a GET request, and doing my research I came to find out that a "request body" was often quite undesirable and perhaps contrary to the RFC standards, and sending a "body" in a GET could result in undefined or unpredictable behavior. But it's all in good fun.