Short definition of oxymoron to make it clear...

An oxymoron (plural oxymora (greek plural) or, more often, oxymorons)("sharply dull" in Greek) is a figure of speech that combines two normally contradictory terms. The most common form of oxymoron involves an adjective-noun combination.
Examples:
-original copy
-organized mess
-cold fire
-wet Sahara

And here's room for ideas. The best one I came up with is:
-quadratic thoughts of Nicolaus Copernicus.
If you have any concept don't hesitate to share