The technique is called Transcranial Direct Stimulation, and while bioethicists are debating whether or not it's ethical to use it to enhance learning in children, hobbyists have figure out how to try it out at home. Think of it as the new Adderrall -- without, apparently, the side effects.
The long term effects of tCDS are unknown, and if you mess up and put orders of magnitude more current through your brain than is typically used in tCDS, obviously, you could kill yourself.
Transcranial direct current stimulation (tDCS) is a technique that has been intensively investigated in the past decade as this method offers a non-invasive and safe alternative to change cortical excitability. The effects of one session of tDCS can last for several minutes, and its effects depend on polarity of stimulation, such as that cathodal stimulation induces a decrease in cortical excitability, and anodal stimulation induces an increase in cortical excitability that may last beyond the duration of stimulation6. These effects have been explored in cognitive neuroscience and also clinically in a variety of neuropsychiatric disorders – especially when applied over several consecutive sessions. One area that has been attracting attention of neuroscientists and clinicians is the use of tDCS for modulation of pain-related neural networks. Modulation of two main cortical areas in pain research has been explored: primary motor cortex and dorsolateral prefrontal cortex. Due to the critical role of electrode montage, in this article, we show different alternatives for electrode placement for tDCS clinical trials on pain; discussing advantages and disadvantages of each method of stimulation.