stop messing with the poor guy
here I will be the only nice one
these cheats are for private online matches only
so you and friends can mess around but if you enable them your score/round won't count here is how to do it.

in the main lobby hold both r1 & l1 and enter this up,up,down,up nothing will happen now start game once game starts you will now have the option to pause so press start (it only pauses your player your friends can still play and works best if your in another area then them I normally wait till they go down stairs and im alone) ok now that you pressed start you are paused enter this up,right,down,left,up,right.down x and a list of cheat will appear choose what you want and enjoy

They were most likely using mods. There aren't any "cheat codes" for this game that you can just enter and have the stuff. The only things in the game close to "cheat codes" are the death cards. But if you are asking if there are any "cheats" for the game that you can just push a series of buttons, then no. Don't believe what everybody else is saying.

i know it!!!! O UP X REALLY FAST WHEN YOUR IN THE lobby before you start!!!! found by me on ps3

dumb dude dont beleive this guy, there is cheat codes and i found out that its works for all consols, so wat u do is get ur console and go on top of ur roof and let it drop, then once its on the ground grab a hammer and just swing at it but while ur swinging the hammer at the console u have to say "give me cheat codes" 3 times very fast and onve u do that just leave it in the middle of the street until a car passes over it but it has to be in front of ur house not the next doors house so then u grab ur console and start cod waw and u will have cheat codes