I think a lot of work is being done by the phrase "have functional value" in your description. Wearing head covering keeps God happy, standing for the anthem keeps you from being harassed in the press. Is all signaling, or all group-membership-signaling silly? Ok, probably yes. And really, for group distinction, the sillier the better.
But this means that almost all online social behavior is silly. Huh, now that I write it, I see how valid the description is.
Using in-group jargon indicates that you are a loyal member of the group , but is actually counter productive to the group 's stated aims of brining its message to the world at large.
Silly Rules (found in the Alignment Newsletter) are rules that do not have functional value in themselves.
Silly rules help groups adapt to uncertainty about the stability of social order by enriching the information environment. They help participants in these groups track their beliefs about the likelihood that violations of important rules will be punished and thus the likelihood that important rules will be violated. These beliefs are critical to the incentive to invest resources in interaction.
Examples:
What formal or informal rules can people use online where things like hats don't work?
One thing that I have come up with since I read this post is
Emoticons. :-)
Reacting to posts with suitable emoticons shows who pays attention and who smiles toward whom - something that is an important signal offline but hard to replicate online.
What are your suggestions?