In CS:S, my KDR was 1:100. After I scored my kill by randomly firing a shotgun after being flashbanged, I realized that I was so incompetent I should simply go back to other games.
In TF2, my KDR is around 1.5 (counting assists) but much higher, at least double, for Engineer and Heavy. How sad that I'm best at playing the 2 most boring classes.
In Left 4 Dead games, I'm certain my KDR is in the hundreds, if not thousands. Zombies die easily.
I used to kick ass at Battlefield: 1942, and had an obscenely high KDR. I once had 200 kills and no deaths in a match on Omaha Beach (Nazi artillery was OP on that map).
Obviously, my best KDR would be in single-player games.
Lately, I haven't been killed in Prototype for quite a while, so my KDR for the past 2 months would be about 10,000:0.
In Oblivion, I have a character with over 1000 kills that has never died.
In Dead Rising, I killed 100,000 zombies in a run that only included 1 death. After that, I was simply sick of the game and stopped playing.
Obviously, it's not as impressive. But now I wonder about the possibility of an online game where thousands fight to take down a single player with god-like powers, and how impressive it would be to kill that player.