This Game of Thrones phrase book will teach you how to speak fluent Dothraki.
Described as a "copper-skinned race of warlike nomads," the Dothraki people can be easily offended, making the process of greeting and parting especially important. The infographic also provides you with some conversational fodder that may be the difference between life or death. Of course, we can't always be walking on eggshells. In the event that you need to defend yourself, the phrase book offers a list of insults. However, you should be aware of the risk of slandering a Dothraki, who may very well respond violently.
Overall, I can't think of a more valuable tool in the Game of Thrones than speaking the native tongue of the Mother of Dragons, making this infographic a handy tool for super fans.