Tried to do a Google search, CW, but I only came up with stuff about a movie named Kiss of Death with David Caruso, the story about the girl who recently died after kissing her boyfriend (she had a peanut allergy and he had just eaten peanut butter), an Italian Thrash band named Kiss of Death and a website that lists the best kisses on film (yes, the Michael/Fredo kiss of death made the list). I could not find anything that talked about the history of the kiss of death.

However, I think it goes back to Judas' betrayal of Jesus. Doesn't Judas kiss Jesus to let the Roman soldiers know which one He is? Not sure, but I think so, and I think that's why it is sometimes called the Judas kiss. Not sure, but that is sticking in the back of my mind.