"Living in sin is the new thing," Britney Spears chirps on her disco-y new song, "3," a paean to Peter, Paul and Mary.
    
No, not the wholesome, 1960s-spawned folk trio. Rather, PPM is slang for ...er, a sexy time that gets a bit crowded.
     
It's always fun to witness a 20-something who believes she/he has discovered a new sin. It's even more fun to witness an aging 20-something who's entered that career stage where she's desperately seeking to remain provocative.
     
"3" is a new track included on Spears' "The Singles Collection," due Nov. 10. Hear it now at  britneyspears.com, or catch the video on YouTube.