If you happen to be a cosplayer, you would be definitely sure of this term. When I heard of this for the first time, I could guess this should be an abbreaviation of ダンスパーティー[dance party]. I was…maybe right, roughly. In fact, this term is common among cosplayers, and it means a dance party for cosplayers. They join this party in order to have fun with dancing…with anime songs. Having said that, lately non-otaku people or those who are not such deep otaku are also coming to ダンパ. And songs are not only from anime but such pop-music. So some cosplayers who love ダンパ or ヲタ芸師[otageishi] could even dance パラパラ[parapara routine]. Yes, I have actually witnessed a group of ヲタ芸師 starting to dance パラパラ after finishing otagei on the main street in Akihabara.
Speaking of cosplayers, I have no experience in cosplay(I wish I could) but I have been to some events for cosplayers such as Comic Market or whatsover. So, I shall introduce some terms those are so common among cosplayers.
1. オールジャンル[all genre]; Like a Comic Market, an event which has no specific theme. So anyone can dress up whatever they want. That means so many attendants would join, so the arena should be such a bigger place like 国際展示場[kokusaitenjijou].
2. オンリーイベント[only event]; The exact opposite of オールジャンル, this event should specify the theme. If an event is for One Piece, only One Piece fans are allowed to join. Also, in BL circles, they can specify even the pair. For example, if the event is for Zoro×Sanji, only those who love this pair could join. I am sure those who love Sanji×Zoro pair never join. XD The good thing of this kind of event, it is much easier to find mates who have the same taste as yours.
3.ナベシャツ[nabe-shirt]; What is it? It’s a T-shirt which is used by female cosplayers when they get dressed as a man. Yes, it is capable of pressing the breasts…to try not to make remarkable. ナベ[nabe] means a pot, but actually it also means a woman who pretends to be a man, or who functions as a male in a Lesbian couple. Incidentally, カマ[kama] means a man who pretends to be a woman. I am not sure there’s also a カマシャツ[kama-shirt] for male cosplayers when they get dressed as a woman(女装”josou”).
4. レイヤー[reiya-]; Yes, it means a cosplayer. If you happen to see a very…umm…hid–us cosplayer, don’t say kimoi(キモイ), but be kind of saying 痛いレイヤー(itai reiya-). 痛い is more modest than any other direct negative adjectives.
5. 肌出し系[hadadashi-kei]; Any characters those are almost naked or wear such dangeroussexy costumes. Otherwise, such cosplayers. I think Rum in Uruseiyatsura is this kind of thing. We can also say 露出系[roshutsu-kei] to mean it. 露出 means exposure.
6. 合わせ[awase]; If you try to be a cosplayer, whatever it is, would you like to accompany some more cosplayers from the same series as yours? If you are in Haruhi costume, would you like to accompany Mikuru or Yuki? Yes, it would be much better, wouldn’t it? So 合わせ means to accompany some cosplayers who get dressed as other characters from the same series.
7. 盗撮の盗撮[tousatsu no tousatsu]; 盗撮 means to take a photo of someone with no permission. Such people are what’s called 出歯亀[debagame] which means Peeping Tom. Well, of course there are a lot of paparazzi called カメラ小僧[camera kozou](sometimes it can be abbreviated as カメコ[kameko]). However, some of them sometimes take a photo with no permission…this is 盗撮. The funny thing is that some paparazzi would take a photo of such Peeping Tom with no permission. This is 盗撮の盗撮. Mostly, such photos would be posted on the net, and saying like “Be aware of those paparazzi.” This is dangeously hilarious…ugh.
By the way, the above image was taken when I went to the event, Chara Hobby 2007. She is wearing a leotard of Char Aznable…umm, gorgeous. (*´Д｀*)ﾊｱﾊｱ However, after I saw this, I encountered a woman who must have been in 50′s and wore the same costume as this…