I was there, and was definitely NOT joining in. Besides the injury part, the wave is an LA thing, and no bay area sports fan should do it.
To suggest the fans "didnt know it was serious" is a lame excuse. Everyone saw them wheel out the stretcher. Most of the fans at the game were a bunch of drunk, pants-sagging, fake jersey wearing tools. The crowd didnt even know when to get loud and when to shut up. Hopefully the new stadium will attract less people with neck tattoos.