In case you didn't know, the name of this site is Kotaku. Did you know that? Some people don't, they just click wildly around the internet like a pyromaniac in a straw factory.
Kotaku isn't a real Japanese word, it's a word somebody (not me!) made up many years ago. "Ko" in Japanese (小) means "small". "Otaku" has a couple meanings, but here it refers to someone who is obsessively interested in something. But shouldn't the site's name then be "Kootaku"? Shuddup.
There are many types of otaku: train otaku, anime otaku, game otaku, Brian Ashcraft otaku, you name it! But if you are looking at ways to i.d. otaku, here are ten — as voted on by Japan's Goo Ranking:
1. He has an anime T-shirt
2. He has an anime shopping bag
3. He has a waist pouch ("fanny pack" / "bum bag")
4. He wears a bandanna (hachimaki)
5. His bag is covered in anime badges
6. His hair is excessively long
7. He wears his rucksack over both shoulders
8. He has big, thick glasses
9. He tucks his shirt/T-shirt into his trousers
10. He wears chemical wash jeans
There are other ways to spot and stereotype otaku, but hey, these are the most popular ways Japan does it!