is a person that is a real prick. he is not coherent and often makes remarks that sound like "aaeeen aaeeen". Another way to spot a yaheen is by the way he walks. If you walk past a yaheen on the street, their is no doubt that forrest gump will be the first thought in your head. you might even sympathise with the fellow and mistake him for a paraolymplian whilst he is playing sports.
the perfect animal example of a yaheen is an ostrich.