Situational irony results from recognizing the oddness or unfairness of a given situation, be it positive or negative. Even though a person typically cannot justifiably explain this unfairness logically, the coincidental nature of the situation is still very obvious to those evaluating it. For example, if the president of Microsoft, Bill Gates, were to win a contest whose grand prize was a computer system, the irony would be situational because such a circumstance would appear ridiculous or "funny" for a number of reasons. Bill Gates doesn't need a computer, he runs the world's largest software company, and he's filthy rich, so winning a computer seems silly and "ironic". This list of half-justified reasons for the oddness of the situation could go on and on but on a very basic level of reasoning all these reasons does really adds up. All can be logically rebutted. Bill Gates has just as much chance of winning a contest like that as anyone else who entered. A computer is a great prize to wins, etc etc. The true "oddness" cannot be explained logically, even though everyone would find that particular situation weird, funny, and "ironic". This sense of being "unfair" or "unfortunate" is a trademark of situational irony. The unusual nature of the circumstances are obvious to everyone and yet, they are not wholly clear when you try to explicate them. Typically the justification for situational irony boils down to someone declaring, "Well, it just is!"