Let the air be mildly radioactive, and that makes it much more conductive - but if radioactivity and ionization are below a certain threshold, the air is still brethable.
Long term effects might be a worry though.
(This is how the very first "radiation detectors" worked - by charging an electroscope's foil arms inside a jar of clean, dry air. The electroscope's arms would visibly repel each other, until their charge dissipated; which would happen at different speeds depending on the air's ionization).
However, it depends on the source of the "zapping".
Zapping may refer to the discharge of static electricity (e.g. you wear rubber, tanked shoes and walk on a synthetic wool carpet. You then touch a grounded water tap. YEOW!). For this kind of zapping you want the air to not dissipate your charge, so no radioactivity, dry air, and the appropriate materials around (wool, synthetics).
Or you want people to be more taserable. This can be done technologically. Usually, tasers work by shooting thin conducting wires charged with a high voltage. But there's research on using ultraviolet laser pulses to "drill" ionized tunnels through the air, with conductivity high enough than a discharge would run through the twin tunnels rather than shorting them out. For this, too, you need dry air (the tunnels must remain isolated) and then it's just a matter of developing the appropriate emitter. You might even have some handwaved "dust particle emitter" that shoots laser-driven conducting particles towards the target, building a pair of ion-and-dust virtual-wire channels. You still have the problem of the last millimeter (which taser avoid by ending the wires with two sharp needles): the ionized tunnel ends on the target's clothes, which might be thick and insulating.
Then finally the spontaneous breaking charge in the atmosphere (i.e. lightning bolts). For that you want conducting air, so ionization, therefore ionizing radiation from some source. Ordinary air breaks at about 30.000 V per meter (you need 300.000 volts to cover ten meters of dry air). Ionizing radiation may decrease that down to about 1500 V/m . Remember that the electric discharge will still try to reach the nearest ground, which might not be the target.
For example: in spontaneous conditions, a discharge from 2 m height will hit a man's head at 1.5 meters if he's grounded, because 1.5 meters is a shorter path than 2 meters. No amount of ionization will allow the discharge to hit the man if he's at 3 meters: the discharge will rather hit the ground, which at 2 m distance will be nearer.
Drilling a UV-laser tunnel from the point source to the man will make resistance lower only on that path. You still will not be able to use more than 60.000 V (because at 30.000 V/m, breakage in normal air will occur at 2 meters). So to hit the man at 15 meters, the UV pulse has to decrease breakage threshold to 60.000/15 = 4000 V/m or lower. And, doing the calculation in reverse, a threshold of 4 kV/m will allow hitting at no more than 15 m range if shooting from a height of 2 meters. Shooting from the hip (at 1 m from the ground) will have a proportionately shorter range.