Someone, typically a female that happens to be insane and likes to have anal sex. This female meets a random stranger in some far off place and within the first 36 hours receives anal sex usually in public settings.
Friend one: So I went Upstate yesterday!
Friend Two: Oh cool, what did you do?
Friend One: I met this guy and we had anal sex in his neighbors backyard.
Friend Two: What the actual fuck? That's disgusting. YOU ARE A FUCKING SHANAL!
To get a stick or pencil, or perhaps even you're finger and casually using it to poke a persons anus whilst shouting 'SHANAL' causing them to leap in surprise.
ahahaha you shanaled him good