When your girlfriend (or wife, or whomever) stuffs her panties in your mouth so that only the tag is hanging out, leaving you looking like a Hershey's Kiss.
Last night, my girlfriend tied me up and Hershey's Kissed me before flogging me. It was fantastic.
Like a rainbow kiss, a Hershey's Rainbow Kiss involves a man and woman to participate in the 69 position on the woman's period. After gathering the sperm into the woman's mouth and the period juice into the male's mouth, this differs in that one or both parties collect the partner's feces into their mouths before swapping.
My girlfriend tried to give me a Hershey's Rainbow Kiss for valentine's day. I gave that bitch a cleveland steamer and haven't seen her since.