Anyone who calls it an "IQ score" is bullshitting. IQ stands for "intelligence quotient" - it's an arbitrary number (called a quotient) that correlates to how many standard deviations you are from the median of everyone that took the test, at your specific age range.
Like BMI, it's largely a 'best guess' at something that isn't so easy to measure exactly - it really doesn't mean anything, but it's handy for keeping track of early development in kids. Anyone who has taken an IQ test after high school either feels like they have something to prove, or is actually retarded (and they're checking on progress for purely medical reasons.)
Yes, I've taken an 'official' one. Yes, I qualified for Mensa. No, I don't care what the number was. Who names an organization of geniuses after the Latin word for 'table' anyway?