This Seeking Tech tutorial will show you how to get the Mama Said trophy and achievement guide in Metal Gear Solid Delta: Snake Eater.
To unlock this, you need to “CQC Slam a guard and knock him out.”
To do so, go up close to the guard. You then need to hold R2 (New Style controls) or Circle (Legacy Style controls) while also holding the left analog in any direction to perform a CQC Slam.
You can find a video demonstration below: