How does an electronic shocker works

When you use transistors in this way, a series resistor must be included in the base line. 10k would be a good guess.

A transistor used this way sort-of works as a switch, but only in one direction. The emitter must be negative side (connected to the ground or - lead of the batetries). Your diagram does not show if this is the case, or whether you were even aware of this issue.

I think what you are looking for is cascoding two transistors as transistors can be CASCADED and CASCODED. that totally depends on the application here is a cascade example, as the output of the first transistor connected to the base of the second transistor "The cascade of a Common Emitter amplifier stage followed by a Common Collector (emitter-follower) amplifier stage can provide a good overall voltage amplifier"

and here is the CASCODE example:

the advantage of using this configuration is to have higher input-output isolation, higher input impedance, higher output impedance, higher gain or higher bandwidth

as I can see from your question, you are dealing with logic gates, or you want to design logic gate. I guess this website is a good start

http://www.allaboutcircuits.com/textbook/digital/chpt-3/cmos-gate-circuitry/