Never heckled, but I've heard an under the breath comment or two.
My favorite experience was the exact oppose of that though. Two attractive 20 somethings, both wearing thongs, were taking instagram-ready photos of one another. They walked over to me, said that it was good to see someone else wearing a thong on the beach, said I looked good in it, and asked me to take their phone to take pictures of them together. it was a really lovely encounter.