The brutal and gory (but yet extremely satisfying) act of a human killing any of the Locust horde in the Gears of War Universe.
Murder, for example by Curb Stomp, Longshot Headshot, Lancer-saw Shredding and Boomshot Oblivion, are just a small sample of hilarious types of Grubicide.
Grubicide is certainly not a punishable act under human criminal law, in fact, it is very much encouraged as the chance of extinction of the human race would be very much likely without it.
Dom Santiago: Marcus, man... I miss my sweet darling Maria! (cries like a lil' b*tch)
Marcus Fenix: For f*ck's sake Dom, stop being a whiny p*ssy! These Locust pr*cks are coming toward us! It's time commit some serious Mass Grubicide!