Someone pointed out in an episode of Cartoon KAT-TUN that Jin called "Kame" during their lie detector skit.
Personally, I believe it. Okay, wait I shall direct thee to the clip first.
Click to view
It was said that around 0:47 you could hear Jin say "Kame". I 'm wearing headphones so it's much easier to hear the audio and for me it was really Akanishi that said it. It couldn't be Koki or Maru because they were still being seen on camera when it was said. Plus, I think I have watched loads of episodes to be familiar with Jin's voice. I really believe it was Jin who said it. Hmm..how do you explain this...
Okay so what if it was him?
Well, you rarely hear Jin calling Kame as Kame or Kazu these days right? ^^;