Look Out Below! (Kills)

is one of the many challenges in Titanfall.

How to Get
The best way to do this challenge is to wait until a group of enemies are accumulated in one spot, then call a Titanfall. The sheer number of people underneath should assure at least one kill. It helps to distract the Grunts or Spectres by allowing them to shoot at you and keep them in one spot while the titan is falling. Keep the minions in the same spot by shooting next to them and body-blocking them so they can't move. The Warpfall Transmitter also reduces the falltime so it's easier to hit those groups of minions. Getting minion kills is probably easiest when doing Pilot Hunter as most players just ignore them, leaving you with plenty of targets.

Another solid strategy is to jump on top of an auto-Titan, thus causing it to kneel, at which point you aim straight at the ground and call in your Titan. Though you only get one kill this way, it is much easier to get these opportunities and it's an almost guaranteed kill.