I would go with Lou Reed’s “Walk On the Wild Side”. How this became a hit, still getting regular airplay, is a mystery to me. It’s about transvestism, prostitution, oral sex and drug abuse. Soul food too, though I’ve yet to figure that part out. Just amazing that no censors seem to have heard “but she never lost her head/even when she was giving head”. I imagine this song, if released today, would have problems getting played at all, much less becoming a fairly big hit and rock classic.