I, myself, have my left nipple pierced, but then, I am a top. You might have your overly sensitive nipple pierced, or even a popular Prince Albert. You set off bells at the airport, and you ring a few bells with me, too.
So, bling it on, bitches! Left means you’re a top with a surprise under that business suit you’re wearing. Right means you’ve got some hardware, but you want to squeal like a pig when I ram your soft, soon to be sore hole.