Learn English – Is this a paradox, oxymoron, or irony

Your college needs to phrase its questions better. You have given a totally acceptable example of what Nordquist ( http://grammar.about.com/od/il/g/ironyterm.htm ) calls situational irony while they probably wanted an example of what he calls verbal irony (antiphrasis). He lists a third type of irony; I've misplaced the article I know I filed somewhere, which lists about six, if my memory serves me right.

An oxymoron is a concise paradox: a phrase of (usually) two words that contradict each other. Strictly speaking, the two halves of the oxymoron should be contradictory when interpreted literally, and the contradiction should be the "point" of the phrase--i.e., the reader should be impressed that such a thing could exist when logically it should not. If an uneducated or unintelligent person solves a problem that stumps the experts, and does it by thinking "outside the box" without being bound by the conventional thinking and assumptions that the experts use, we might call it brilliant stupidity. It is a device that is best used in literary and philosophical contexts, as opposed to ordinary workaday writing. Many people also use the word oxymoron for phrases that are not self-contradictory, but can be made to seem so through wordplay, as with jumbo shrimp ("shrimp" meaning both a type of crustacean and something that is small) or military intelligence ("intelligence" meaning both the collection and analysis of secrets and the quality of "smartness," with the added implication that the military is not very smart).

Your sentence is not an oxymoron according to either sense of the word, because the two halves of the supposed contradiction are not together: "I hope the events at the Olympics will be uneventful". The literal juxtaposition of two contradictory ideas is a key element of an oxymoron; if they are separated, it is merely a contradiction. If the two words were together--"uneventful events"--then it would fit the second, broader definition of an oxymoron, with two slightly different meanings of the root word event being used to create an apparent but superficial contradiction.