*edit* and if anyone wants to help, i am trying to figure out the best way to kill a player without them freaking out on me.
Fast poison, knife in the neck, or gunshot to the brain-pan are your best bets.
The key to killing folks without freaking them out is to make the entire event a surprise. They shouldn't even be aware that they are in danger (this is why sleepy-time is a good choice), and you should use a method that kills them before they can realize anything is happening.
Of course, killing your friends (or even just players) is terribly rude, highly illegal, and shouldn't be done.
Now, when it comes to killing
characters, the real deciding factors are 1) maturity of player, 2) method of demise.
1) Some players cannot stand to have a character killed. Ever.
Other players have so many character ideas that they really don't mind losing a character every couple of sessions, since it gives them a chance to play something different.
Decide which kind you're dealing with, and how much "freak-out" you're willing to deal with. That will give you an idea of how mature the player is and how careful you'll have to be during the killing.
2) For most players, how their characters die is crucial to how accepting the player is. Going out heroically, as part of a great battle against evil; dying in a cool, stylish, and very final way; making a heroic sacrifice; all can work tremendously well, especially if it feels climactic. Suddenly knocking their heads off with a random and nameless giant is a lot less cool.
For your purposes, the real trick will be to make it seem fair, instead of looking like you're trying to kill the character. This will be especially challenging since you
are trying to kill the character.
Good luck.