Tesla minigame is the one on the channel select where the guy is holding the box with the two lightning rods sticking out on top.
I got this achievement while also going for the six pack achievement (since the helmet and backpack let you know what the Kinect is tracking as a person). No matter what I tried, shooting the little devices on the ground did not pop the achievement, however when I accidentally zapped another 'players' backpack, the achievement popped. Since the backpack has 'Tesla Coils' on it, this would be the Tesla device the achievement is referring to.
I don't know if you can do this with the one you are wearing, but it isn't to hard to get a second 'person' tracked.
EDIT: Heid has confirmed that you can do it without a second 'person' by aiming at your own backpack, over your shoulder.