As someone who has actually hooked not only his own head but the heads of friends and family up to 9-volt batteries (not to the temples for performance, different part of the head for different reasons), I felt the need to register to call you all wusses.
I'm totally gonna read more into this and try it out if it looks promising.
Seriously! It's fun! Just do your research first!
First off, note the current limit: 2mA. Ohm's law states that Voltage / Resistance = Current, so you've got to find the resistance of your head and tweak the voltage to get the right current. With a nine volt and the area I was working with (mastoid process, behind the ears), it came out to about 10mA depending on how hard you pushed with dry wires. That was about perfect for my purpose and it worked out great with no lobe damage (that I've noticed (yet)).
Secondly, do your research! There are plenty of papers about hooking electrodes up to brains. It is entirely possible to do this safely at home. It is also entirely possible to really zap the hell out of yourself, possibly fatally.
For the curious who may be asking "Why in the hell would you wire your mastoid process to a 9-volt?", you remember that story a few years back about how the Japanese made a headset that let you remote control people? Turns out that works by sending about 10mA through the inner ear by way of the mastoid process, causing you to feel like you are tipping over. I don't know about you, but I couldn't resist verifying that. BTW, FYI, totally verified.