Board Thread:General Discussion/@comment-10266932-20130531151056/@comment-11477779-20131210103812

I'm guessing it's a giant Caps Lock key and the release command is "Annoy!" :D

I could swear I read, saw, (imagined?) that once you've obtained Bankai, you can release your Shikai without saying the release command. I seem to remember this around Renji and Byakuya's fight before Rukia's execution.