Fold and unfold the flap not quite halfway. Sink the two areas triangularly. Note that the crease does not go point to point. Outside reverse fold. Pull out two small hidden flaps.
Outside reverse fold the horn from the center of the head.
Be very creful, it is easy to tear off the horn at this point. You may need to use a paper clip or tweezers. Thin the horn further by sinking it in half. Crimp fold the ear. Complete the ear by flding the flap back to form a point.