A phrase from Unreal Tournament and Unreal Tournament 2004 used as an award for getting 6 kills in a short amount of time. The effects in the sound are the letter M skipping 3 times (hence M-M-M-) and the word Kill echoing three times.
Awards preceding Monster Kill are Double Kill, Multi Kill, Mega Kill and ULTRA KILL, with LUDACRIS KILL! and H O L Y S H I T! coming after Monster Kill.
UT Announcer: Double ki- Multi kill! Mega KillULTRA KILL!!! M-M-M-MONSTER KILL!
(note: the reason multi kill and mega kill are shortened is that usually the player is getting kills so quickly that there is not enough time for the announcer to utter the entire phrase and it is cut off, replaced by the next award sound. The ULTRA KILL phrase is also commonly completely replaced by the announcement of Killing Spree, when the player scores 5 kills without dying.)