adj By distinct definition it means a half smile half grin. But it could be taken into context as a state of how a person feels.
Most often used in text messaging or instant messaging. Anything with distance involved to describe what a conversation has done to the other person with the lack of an emoticon.
Girl:You are awesome
Guy: I have a smrin for you right now
Guy1: We are going to go out and get drunk
Guy2: Smrins all around here for that idea.