Milnor's Doodle

This is an immersed curve in the plane which bounds
two different immersed disks, interchanged by reflection.
It is a good exercise to find the disks (see doodle). Supposedly, John
Milnor was doodling during a lecture one time, and came
up with this picture.

Reference:
Poénaru, Valentin,
Extension des immersions en codimension 1 (d'après Samuel Blank). (French)
Séminaire Bourbaki, Vol. 10, Exp. No. 342, 473--505,
[Extension of immersions in codimension 1 (after Samuel Blank)]
Soc. Math. France, Paris, 1995.