Hey Everyone! 
最近はなんか暑かったり、寒かったり、温度差が激しいから風邪ひきそう。 
みんなはちゃんと体調管理してる？
To day we will be covering…
大きいお友達 
When you hear this phrase what do you imagine?
Do you think of a physically big friend? Kinda like Baymax?
A friend that likes to eat a lot?
Someone who has many friends/connections?
It is actually none of the above. This internet slang actually refers to adults (usually male) that are very into (as in VERY into) anime, manga, or shows that are targeted towards children.
Origin 
Like some of the other slang I have introduced before, this one is one of those rare words that did not originate on the internet. This one is actually speculated that it originated during a Sailor Moon (very popular at the time) event that was held in the 90’s. During this event there were adult fans that acted in such a way that made the kids that came to the event cry. When this happened, one of the voice actress that was there for the event, 久川綾 （ひさかわあや）, used the phrase 大（おお）きいお友達（ともだち） in a sarcastic way to criticize these adult fans. It is also said that it is possible that one of the main hosts used this phrase during the event.
Although the incident described above is the most famous and thought to be the origin story of this phrase, no one actually knows for sure if this was the first time this phrase was used. There is a theory that the creators of another anime that was aimed towards kids during the 80’s referred to their adult fans as 大きい友達, but when the producer was asked about this years later in an interview, he denied that they used this phrase.
Am I an 大きいお友達？ 
Although 大きい友達 is used to refer to adult fans of content aimed towards kids, not every adult who is a fan is considered as an 大きい友達.
So what is the difference between a normal fan and a 大きいお友達?
People will be considered as a normal fan if they are simply enjoying the content and not ruining the magic for the targeted audience.
Here are some things that would make a person into a 大きいお友達：
- Going to an event aimed at children then flocking to the voice actors/idols without any consideration of the kids at the event
- Taking over the front row at a children’s event so that they could get the sickest pictures of the voice actors/idols (often done by setting up cameras, which makes it even more difficult for kids to see what is going on)
- Buying up merch, making it harder for the target audience to get
- Manipulating offline/online votes to get the outcome they want
- Posting vulgar content on official bulletin boards (which usually leads to the production company closing the boards)
As you can see 大きいお友達 is usually used negatively and refers to adult fans that basically act like children with money. Although this may sound like a minority, it is a big enough problem that some events will not allow adults, unless you are accompanying a child, or they will hold separate event for children and adult so that the children does not have to suffer due to inconsiderate adults.
However, depending on the genre of the content, it is said that some 大きいお友達 will step back so that the target audience could enjoy the event. Although these people call themselves 大きいお友達 to be self-depricating, I personally think these are just normal adult fans that has common sense.
大きいお友達 on the internet 
Although this word originated before the spread of the internet, it has been used a lot on the internet, especially on boards and forums that relate to content made for children. As mentioned earlier, this word has a negative nuance and because of this, when it is used in real life or on the internet, it is used with the intent of insulting these kinds of fans (passive aggressively).
Let’s take a look at some examples:
大きいお友達の皆様、小さいお友達を先に並ばせてください。
- Dear adult fans, please let the children line up first. (Nuance: Hey big fwends, pwease let the little fwends go first)
何度注意しても、大きいお友達が不適切な投稿を続けるため、この掲示板を閉鎖させてもらうことにしました。
- We have decided to close this forum because the adult fans continued to post inappropriate material, no matter how many times we warn them. (Nuance: This forum is getting shut down because ‘surprisingly’ the big fwends couldn’t behave like actual adults)
また大きいお友達たちが新発売のおもちゃを買い占めたらしいwww。子供のことなんか考えてなくて草
- Apparently, the adult fans bought up all the newly release toys again. It’s funny how they don’t think about the kids LOL.
Example with furigana
大（おお）きいお友達（おともだち）の皆様（みなさま）、小（ちい）さいお友達（おともだち）を先（さき）に並（なら）ばせてください。
- Dear adult fans, please let the children line up first. (Nuance: It is ridiculous that we have to even say this, but please let the little friends go first)
何度（なんど）注意（ちゅうい）しても、大（おお）きいお友達（おともだち）が不適切（ふてきせつ）な投稿（とうこう）を続（つづ）けるため、この掲示板（けいじばん）を閉鎖（へいさ）させてもらうことにしました。
- We have decided to close this forum because the adult fans continued to post inappropriate material, no matter how many times we warn them. (Nuance: This forum is getting shut down because ‘surprisingly’ the big friends couldn’t behave like actual adults)
また大（おお）きいお友達（おともだち）たちが新発売（しんはつばい）のおもちゃを買（か）い占（し）めたらしいwww。子供（こども）のことなんか考（かんが）えてなくて草（くさ）
- Apparently, the adult fans bought up all the newly release toys again. It’s funny how they don’t think about the kids LOL.
This word is sometimes shortened as 大友. If you see this it is talking about 大きいお友達 and not ‘best friend’.
子供向けコンテンツのファンであることは全然悪くないと思うけど、大きいお友達にならないようにだけ気をつけよう。子供向けイベントでは子供達を優先しよう！
Fuga
If you missed the previous posts, you can check them out here!