Green Eggs and Ham

Son loves Dr. Seuss' classic Green Eggs and Ham. About two weeks ago I finally made green eggs and ham. We had delicious nitrate-free ham and I had green food dye in my drawer. All I did was squirt some green dye on the egg yolk and Son ate it. It would be more uniformly colored if I had scrambled it, but in the book it was made a la sunny side up. Here Son is smiling while eating his green eggs (which in the end he was distrustful of -- ha). On the other hand, he devoured his ham slices really fast. Why is the color green not easy to take when it comes to food for most people, especially kids?