“3,” the latest single from reformed train wreck Britney Spears, is tacked on to a contractually obligated best-of, but it doesn’t feel tossed off. Max Martin helmed the production, and apparently some thought was put into generating controversy: The song is very much about three-ways. The post-collapse Spears era has already birthed some pretty good singles (“If You Seek Amy,” most prominently, although we prefer “Womanizer”), so don't call this a comeback. Just know that the song works — it’s big, bright, and harmless, if also instantly forgettable. In any case, that part where she goes “1, 2, 3 / Peter, Paul, and Mary” is pretty funny.