1. Change the guns on multiplayer to frag grenades.
2. Set up a multiplayer match (casual warzone is the best choice) with you and 1 bot.
3. Whilst in the match pick up the frag grenades (doesn't matter how many you pick up).
4. Down your enemy.
5. Equip your grenades and hit your enemy with B and as soon as you have, click A to pick the enemy up, the round will end but the enemy will explode in your arms.

If you have done this right the game will say you have a kill towards the achievement, as the enemy Will have saved your life from the explosion.