Jolting Jacks are the blue teleporting Nova Crawlers. When outside, they spawn on the rooftops of the houses. They mostly spawn in the beginning of each round.
I highly suggest using the Acid Bomb equipment for this trophy as you get 3 of them and they stick on the Jacks, so you don't have to time with a cooking grenade and can throw them directly on the Jacks.
The best area to do this is in the garden of the Prisoner Holding (turquoise) house. The roof is low so hitting the Jacks is fairly easy, and there are 2 possible spawn points.
Using the Equip Mint elixer is very recommended and if you're willing, a Cache Back elixer would help too.
Also, if you already used your elixers and Acid Bombs and it's not a dog round, you can check the shed in the garden of the Yellow House to see if the drop in there is a Max Ammo.
Because of the limited spawns and grenades this can take quite a few rounds to complete.
Here is the video of me doing this: