*** NOTE: This achievement is no longer attainable as the servers have been shut down. ***
I found it fastest to just play the Executive Suite map and take turns throwing each other down the elevator shaft. Just break the elevator door, and every time the bass hits, the doors will open. Once you get the timing down, this goes very quickly.
My suggestion is to enter a lobby (a "Hood Hangout") with a friend, invite your friend to a ranked match on Executive Suite, and then rematch after each match. It will take ~6 hours to boost all 400 matches (200 wins each) for the Ornery Bastard achievement using this method.