A reference to a funny animation from fat-pie.com. Spoken when someone that looks like a creepy stalker/molester is spotted. Characterized by long face, balding and blond, long mysterious coat, glasses, and at least 45 years of age. Hands in pockets are a plus if tallying for points, as are balloons and candy giveaways. Also used as a code phrase if said "Morgan" is within earshot and you can't say "That guy is creepy".
Holy crap, man, that's one of the best "He is called Morgan"s I've seen this month, over there, by the park bench.