My case might be a little interesting. I have always had one elbow, my right elbow, that makes a very loud snapping sound. But something I never hear with the left elbow, or it could be that I just use the right arm much more when I prop myself up in bed to get up or move my position when relaxing as that is the only time I ever hear the very loud snapping sound. The sound is loud but there is no pain involved and it happens I would say 90% percent of the time. My mom having one ( I believe it is just one) double jointed elbow, I always just chaulked it up that I may have some slight abnormality with that one specific elbow. I learned that I have one hypermobile thumb, but only one thumb, something I had not even known until an ex one day discovered when playing with my hands. To add to that there is my buckling and weak ankles, but only a problem when I wear heels and never an issue when barefoot or in regular shoes, so it probably is not even a real legitimate abnormality at all. Still, it's something I have always wanted to have examined and x-rayed by an ortho, but mostly for curiosity sake.