Bring Me the Head of Charlie Brown

From Wikipedia:

Bring Me the Head of Charlie Brown is an animated short directed and animated by Jim Reardon, who would later become director and storyboard consultant for The Simpsons. The cartoon was made in 1986 while he was at CalArts.

Probably apocryphal anecdote from the YouTube comments:

According to someone I know in the animation trade, Charles Schulz was shown this on video at an animation convention. Jim Reardon and friends supposedly managed to talk Schulz into watching the film to get his opinion. He reportedly sat silent and motionless as he watched it. After it was finished he stood up, cleared his throat, and said, "Very clever, very funny, but just don't do it again, okay?" That was it.