(I'll still reply 2.5 years later) It's in your continuum instal folder. From there go to sounds folder, they are listed as bong. The one you want is called bong6. These files are .wa2, but you can simply change them to .wav and open them in a common media player.
Yes for the person that last killed you just use %killer You can also use %killed %area %coord %tickname (tickname is the name you have selected in the F2 or page up & down list) There are other ones as well, I think there are listed in the F1 menu in game.