Pagan

Channel 4's The Fried Chicken Shop: Life in a Day is a one-off documentary about a fried chicken franchise in Clapham. Over 24 hours they speak to the staff and customers as well as eavesdropping on their conversations. At one point, one of the kids from the local college says something like, "Don't be a pagan, pass the ketchup".

Exhibit A

It's been a fair while since I was last in contact with the real word(s) on the street, but now and again, a friend who is still in higher education brings me up to speed. It was from him that I first heard pagan  to describe someone who would grass you up or betray you quicker than you could say "follower of a nature-based religion". He said it doesn't just have to mean a two-faced snitch, it could just mean some kind of loser, and that seems to be the way it was used in the programme. The negative aspects of being a snitch have broadened to describe anyone acting in a negative way.

It seems that many of the people who use pagan in this new sense, however, are not really aware of its other connotations, so it's not clear exactly if this term is coincidentally the same as pagan in the sense of wicca, or if someone with a grudge against non-Abrahamic faiths decided to equate them. (the latter scenario might not be implausible: at school, where there were a lot of Muslims, infidel was a pretty bad word, as was heathen, so pagan isn't really that far off).