A troper hits upon a concept they think is universal, which has nevertheless evaded the wiki's attention until now. So they start a thread on TLP, with a title and... not much else. "It pretty much explains itself," they say.
Most of the time, unfortunately, the title is overly vague or completely opaque to everyone but the original poster — anything but Self Explanatory. Sure, we know what theremins are, but how exactly are they a trope? And what the heck are "Southies"? We're not idiots, but we're not mind readers either. If it really is self-explanatory, then you could say it is, but explain it anyway, because some of us Viewers Are Morons.
The moral of the story: Explaining yourself never hurts, and it's the best way to prevent your thread from dying prematurely of confusion.
A corollary of this is that no example is obvious, even if it's from Neon Genesis Evangelion. No, especially if it's from Neon Genesis Evangelion. You should also not make a Zero-Context Example, "One word: X," or "X. That is all." Even if, for instance, you put your Axis Powers Hetalia References into Anime & Manga section, most readers, seeing "Russia. Just Russia." will be thinking of the country.
Another corollary is to not assume the exact nature of a trope based on its title alone. Read the description before you make any comments or examples.