Well I'm happy to use "costly signalling". I was under the impression that costly signalling was signalling. If it isn't costly, at least for potential fakes, then I'm not sure how it can serve as an explanation for behavior. Why should I signal when the fakes can signal just as easily? What is there to gain? I think at the very least, there has to be some mechanism for keeping out cheats, even if it's rarity. From the wikipedia article on signalling theory:

" If many animals in a group send too many dishonest signals, then their entire signalling system will collapse, leading to much poorer fitness of the group as a whole. Every dishonest signal weakens the integrity of the signalling system, and thus weakens the fitness of the group."

But what am I? Some kind of prescriptivist? Evidently my understanding of the term is a minority, and people far cleverer than I don't use it my way. I'll stick to "costly signal" in future.

“No! I must resolve the muddle” he shouted

The radio said “No, Patrick. You are the muddled one”

And then Patrick was a zombie.