Again, we don't include notes like the one suggested that are usage notes on the English gloss rather than the Japanese word. The point I was making about 2ch is that it's splintered into 5ch and a new 2ch (at a different url from the original) which apparently isn't half as popular as 5ch,so it doesn't really make sense to speak about 2ch any longer.
Please, don't resubmit basically the same edit upon rejection accompanied by another wall of text.

https://en.wiktionary.org/wiki/Category:English_4chan_slang

One ref to confirm at least "esp. 4chan".  Having looked, I'd say "uncommon outside" is a fair appraisal.
https://en.wiktionary.org/wiki/summerfag
(Internet slang, derogatory) A new, inexperienced, and presumably teenage user who joins an online community (especially 4chan) during the American school holidays at summer 

Original ref. in 2018 was to "2ch slang". This seems essentially correct.

Thank you for the feedback Marcus.  I have definitely gotten comments over time, which I certainly would not deny.  Very recent comments, outside of one notable one, I have not caught up with yet.  So if there is a flood of perturbed messages, I just haven't seen those yet. That's on me.

Because "fag" is a touchy term that risks offense (why I was trying to edit), I'll try again with something brief:  "summerfag" is a term limited to a specific community, 4chan, which has a practice of appending "fag" to a lot of terms.  The ref gives 20+ examples. ie.
newfag (new member)
oldfag (long-time member)
samefag (someone who replies to their own posts anonymously)
....

These are generally limited to this community, and not a reflection of general English or even general [net-sl]. This is [4chan-sl].  夏厨 seems quite a bit more common in general use outside of 2channel than "summerfag" outside of 4chan. Since "fag" risks extreme offense, and since "summerfag" is not well known outside of a specific community, I think warning flags are appropriate. 

2ch/2chan/2channel, whatever. Googling "2channel" will work.  I didn't realize this was in other entries, any version is fine with me.

@@ -14,2 +14,2 @@
-<gloss>summerfag</gloss>
-<gloss g_type="expl">young and inexperienced user who joins an online community during the summer</gloss>
+<gloss>summerfag (uncommon outside of the online community 4chan)</gloss>
+<gloss g_type="expl">young and inexperienced user who joins an online community (esp. 2channel) during the summer</gloss>

@@ -12 +12,2 @@
-<misc>&sl;</misc>
+<misc>&net-sl;</misc>
+<misc>&derog;</misc>

nicopedia  hatena
http://shii.bibanon.org/shii.org/knows/2ch_slang.html
https://en.wiktionary.org/wiki/summerfag
g ng 
夏厨	43010