Ok so I was wondering about this. As we know, it is extremely hard to kill a Saiyan if you are a normal human. But what if they attacked them in their sleep? When Krillin threw a rock at Goku it hurt him since he was sleeping, obviously off-guard. There have been times, like when the old dude hit Goku on the head with an axe, but he was looking right at him and on-guard so it didn't hurt him. If you attacked one in their sleep, wouldn't it be possible to kill them? Thoughts?