Start up a 1v1 private match and invite your friend. Set the Time Limit to 10 min (even though that won't factor in your boosting). Set the score limit to 500 points and the Respawn time to 0. Go to the "Resort" map.
You will get this on your quest to get 100 total kills, which is a trophy on it's own. This trophy will pop after you get your 50th kill.