Imagine just sorta barely getting nicked by a lycanthrope so whenever a full moon comes around you only get the ears and the tail and some truly unusable paws… maybe some other traits too, but the point is, not all of them. Nothing happens to your mind, either. You just become a silly and very clumsy demihuman and that’s it :3
that or it's the summer and you're near a pole, such that the moon only barely grazes above the horizon