Arika Okrent writes:

Gone are the days when you could have a show about a fantasy world where characters spout random, made-up gibberish as their "language." When you put a lot of thought into the costumes, weaponry, and hair styles of your invented culture, you had better give it a proper language too. That way motivated fans—and there will be fans this motivated—can figure out the system to it and even learn to speak it themselves. The producers of Game of Thrones did the smart thing when they hired language creator David Peterson to work out realistic languages for the show. This season fans will be getting to know two new languages, High and Low Valyrian. But before you start trying to tackle those, here are seven cool facts about the language from the first two seasons, Dothraki.

My favorite factoids from the article:

The Language Creation Society was founded in 2007 as an organization where people who invent languages as an artistic and intellectual hobby (known as "conlangers" from "constructed language") could share their work and promote their craft.

Dothraki has more than 3000 words and a full grammar: Learn Dothraki.

Peterson turned his wife's name, Erin, and into the Dothraki adjective meaning kind or good, from which is derived the verb "erinat" (to be good) and the noun "erinak" (lady, kind one). The word "okeo" is a tribute to their beloved cat.

Dwight Schrute of NBC's The Office extended the grammar by using a "Schrutean compound", which is now named for him!

When actors ad lib Dothraki on Game of Thrones, it gets retrofitted to the grammar!

Dothraki is like the Klingon of the 21st century. Lots of folks speak it at Comic Con!

DOTHRAKI HAS TONGUE-TWISTERS:

Qafak qov kaffe qif qiya fini kaf faggies fakaya.

Say it three times fast. It means "the trembling questioner crushed the bleeding boar that squished a kicking corn bunting." Hear it here.

AWESOME DOTHRAKI IDIOMS:

Athastokhdevishizar: Nonsense (lit. "fog talking")

Hash yer dothrae chek?: How are you? ("Do you ride well?")

Shierak qiya: Comet ("bleeding star")

Ki fin yeni!: WTF! ("By what failure!")

Thirat atthiraride: To dream ("to live a wooden/fake life")

Fonas chek!: Goodbye! ("Hunt well!")