The words below all connote a lack of seriousness. Make sure these words do not apply to your SAT prep (which you should take very seriously!).
Flippant means not showing the proper respect. The situation is usually one that calls for a certain amount of gravity, say church or class. The flippant student will lift up his seat and ask the teacher, “Where should I go” when she asks him to take his seat.
Certain occasions call for the utmost seriousness, just as certain ideals are held in high regard. To behave irreverently is to snicker as the Queen of England walks by. To speak irreverently as to poke fun at a topic that most take very seriously.
A perfect example of irreverence is found on the Daily Show. For decades news shows have always been an occasion for seriousness. Some octogenarian, with a toupee that is as obvious as his cue-card reading, intones about events in Congress with the same gravitas reserved for funeral processions.
Enter Jon Stewart, who in the last ten years has turned the news hour into a laugh-a-thon as he lampoons political candidates, other news shows, and just about any topic that most would think beyond the pale of satire. Jon Stewart is irreverence personified.
Life is important, and one who does not take it seriously can be accused of being frivolous. Unlike ‘irreverent’ or ‘flippant’, frivolous doesn’t relate to belching in the pew or poking fun at political candidates. A lifestyle can be frivolous (just tune in to any celebrity reality show). Of course if you revere the Kardashians then my comment may seem downright irreverent.
To be facetious is to knowingly poke fun at serious topics. A facetious remark is one that shows that the speaker hasn’t treated the subject with the appropriate level of seriousness. The idea with facetious is it is not as pointed as irreverent, and hints that the speaker, after making an inappropriate comment, may become serious again.
For the SAT it is not vital that you know the nuances between words (though knowing them will surely make you a better writer). For the words above, think of them as meaning lacking the proper seriousness.