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 Hetalia: Axis Powers references into the 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.