I always thought the boys were singing "on the left now OR right," to suggest they could be versatile.
But you know what it means when a guy says he's "versatile" anyway: BOTTOM! 
Btw: When I got my ear pierced oh, so many years ago (early '80s), I asked the girl at Piercing Pagoda (really!) what either ear meant, and she told me that the left ear was "gay" and the right ear was "drug dealer." I told her "left--definitely."
Years later when I had my nipple pierced, I decided to have my right nipple done, just so all my jewelry wouldn't be on the left side of my body. 
\"...a once in a lifetime feeling that returns every week...\"
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