A reversable quotation, like the two Sorensen quotes provided by boccaccio and the first three by Aurelius are chiasmi (or whatever the plural for chiasmus might be). The originating quotation for this thread may well also qualify as a chiasmus, but it seems to me not to be a particularly good example.
A parallelism (according to Webster's New Universal) draws a parallel between one thing or idea and another. Just how that would differ from a simile or a metaphor eludes me. (And that's brings up a point that's bugged for for quite a long time: Just what IS a meta for?)
I wouldn't have the least idea how to categorize Aurelius's Kermit quotation, but it seems to be a close relative of the non sequitur, which I was just discussing with Alex last night and hoping she wouldn't introduce as a topic.
Grammatical taxonomy is NOT my forte, contrary to what Alex would have you believe -- trivia is. Keeping this essential fact firmly in mind, I would call all of red-vixen's examples 'contradictory adjectival descriptions', strictly for obfuscatory reasons, you understand.
Nikka's example seems to me to be a legitimate juxtaposition, for which definition I refer to Alex's original criterion (or whatever the singular of criteria may be), "opposite phrases placed side-by-side to give impact".
I like boccaccio's Steven Stills quotation and the one with which he closed his thread, both of which seem to have some elements of the chiasus and some of the juxtaposition.
Here are a few others: "I am the tallest short guy I know."(Mel Brooks) -- some juxtapositioning going on here, but I would classify it as more irony than anything else.
"We had to destroy the village in order to save it." -- more irony, unintentional this time.
"Man, when I tell you she was cool, she was red hot; I mean she was steaming."(Thin Lizzie - 'The Boys Are Back In Town') -- I'd call that a juxtaposition.
"She blows hot and cold" -- that's an advertisement.
If we refer back to Webster's, "a placing, or the situation of being, close together or side by side", I think we'll find that the ultimate juxtaposition would be of a boy and girl. (Which brings up the question, "Just which position IS the juxtaposition and what does it look like when it's at home?" -- non sequitur.)