UnNorman
When someone, usually named Norman,

who is typically a backstabbing cocksucker, starts acting nice for no reason tipping you off that he's up to something.
Jay: That damn Norman is up to something
Andrew: How's that?
Jay: Yesterday he was busy trying to fuck me in the ass with the boss and today he's acting like he's my best friend!
Andrew: Whoa! Totally UnNorman! Watch your back bro!