If these are so well-known, why don't I ever see people use them as account names, like on a forum, as a joke?

Scripting Security Descriptors.doc

Table 1  Well-Known SIDs
Account or Group SID
Everyone S-1-1-0
Nobody S-1-0-0
Anonymous S-1-5-7
Authenticated Users S-1-5-11
Administrator S-1-5-<domain SID>-500
Guest S-1-5-<domain SID>-501

Well, most of them don't make so much sense to pick... Calling yourself "Everyone" on a forum is not that good of a joke?.

Eh?

Great, a new trend....  First it was yL and then anti-yL....  Now we've got guys using SIDs.... 

What do all three of those have in common?

They all have an 'i' sound (if you say S-I-D)

[quote author=hismajesty[yL] link=topic=10168.msg95034#msg95034 date=1105577830]
They all have an 'i' sound (if you say S-I-D)
[/quote]Nope, try again.

They're all stupid trends?

[quote author=Adron link=topic=10168.msg95073#msg95073 date=1105629568]
They're all stupid trends?
[/quote]Ja, and I started them all!

nonono, I believe I started anti-yL sir.

But without him starting yL, there'd be no anti-yL. But it seems as if Eibro has left yL, making me the only yL left and you the only anti-yL left. It's on.

Ah Eibro left yL?  Hope he joined vL, at least, I think he should.

[quote author=hismajesty[yL] link=topic=10168.msg95111#msg95111 date=1105653447]
But without him starting yL, there'd be no anti-yL. But it seems as if Eibro has left yL, making me the only yL left and you the only anti-yL left. It's on.
[/quote]
Bring it  <_<

[quote author=Adron link=topic=10168.msg95073#msg95073 date=1105629568]
They're all stupid trends?
[/quote]

[quote author=UserLoser link=topic=10168.msg95679#msg95679 date=1106089406]
[quote author=Adron link=topic=10168.msg95073#msg95073 date=1105629568]
They're all stupid trends?
[/quote]
[/quote]Sie werden sich hinsetzen. Sie werden ruhig sein. Sie werden nicht beleidigen Eibro.

I thought that was some odd form of Hebrew.

No, it's German. 'Sie' is a dead giveaway, IMO. 'hinsetzen' is also kind've a dead giveaway too, since it's usually the German language that combines t's and z's together. But, let's try a translation from German to English just to make sure that it actually makes sense.

[quote author=freetranslation.com]They become themselves hinsetzen.  They will be quiet.  They will not insult Eibro.[/quote]
As you can see, the only word it stumbles on is hinsetzen. According to google, it means "put".

The same phrase translated by google:
[quote author=google.com/languagetools]They will put themselves.  They will be calm.  They will not insult Eibro.[/quote]

o.O i see..