I must hypothesize that Don Hertzfeldt's spoon and banana were symbols of a penis and vagina. Though no one would typically eat a banana with a spoon unless the banana was in cereal or perhaps mashed into some kind of dessert but I have heard sex referred to as "mashing" that pussy, so maybe the mashed banana was referring to a vagina needing to be mashed by a large penis.

My spoon is too big. My spoon is too big. My spoon is too big.
You can feel the frustration of having a penis that is too large and no woman would want it.
But then along comes the giant walking banana.
I am a banana.
And everything is set right with the world. The giant walking banana can be mashed and eaten by the giant spoon. Or the enormous gaping snatch finally finds a penis worthy of its incredibly wide diameter.