My worst ever k/d was somewhere from 15-18 kills and like 56-64 deaths, but I can't remember the exact score. The reason I did so bad was because I was in a game with an entire team of 15th prestiges against me, who at the time was a 1st prestige, and some other non-prestiges.
Anyway I just got through with a game with a horrible teammate. So I was playing Domination on Stadium ( 1 of the new maps ) and got a Care Package, and to my surprise it was a Blackbird! So I start to retrieve it, and right as I finish taking it some guy on my team ( who I'd describe with words not allowed on this site :P ) with the perk Hardline Pro changes my care package to an RC-XD! I was incredibly mad because I rarely get anything good from care packages, and when I finally do a guy changes it.
Sorry for the Rant, but that made me very mad. Btw I did get a kill from the RC-XD.
Also earlier today I had a pretty good game. Went 18-7 and got a 12 kill streak ( should've had Dogs equipped

) and managed to level up during the game.