Hey, i'd just like to point out the rules, because other people have accused me of that too...

What is flagging?

If you are not currently winning a game, you will have the option to 'flag' to the players above you. You do so by clicking the flag in the lower right hand corner:

What this means is that you will automatically drop out of the game when there are only as many people left alive as the spot you flagged for. For example, if you flagged for third and only three players remain, you automatically drop out.

Flagging does not prevent you from attacking or from stronger players attacking you. It only signifies that you cannot finish higher than the position you flagged for. Often times, but not always, this will mean a stronger player may leave you alone to attack a non-flagged player

From http://kdice.com/FAQ#flagging