The song "Abba Zaba" from his debut album Safe as Milk (1967) has a zany, nonsensical, and cartoon quality to it, mixed together with a kind of jungle menace. If a mysterious spaceship were to land on Earth, I imagine Abba Zaba would be the song howling its way out of the vessel when the doors finally open and the alien prince steps out to greet us. His face would be adorned with an ancient mask, reminiscent of something African, and he'd be wearing a top hat and a fake mustache. Bongos would be hanging from his neck.
For people who have listened to Beefheart's more famous album, Trout Mask Replica, and didn't like it, Safe as Milk is a good way to open the door to appreciating some of his more challenging work (as is THIS one hour documentary).
Here is another song from Safe as Milk, followed by pictures I found by searching for images using phrases from the lyrics.