This achievement should be one of the first you acquire because it happens A LOT in this game.
Simply wait until you spot a Jockey coming for your team, grab a
weapon suited for dealing damage in short amount of time ( shotgun is a good candidat ), wait for the Jockey to jump on a Survivor and
make him meet his fate as fast as you can.
When he's dead you gain this achievement and your friend owes you one !