The Mad Vandal.

National Lampoon had a weekly Radio Hour that I stayed up late to listen to in the mid-70s. I fondly remember a couple episodes about "The Mad Vandal," done in first-person voice-over detective style with "Chuck Farley, Safety Patrol" as the narrator. Also called "High School Confidential," the story told of someone smearing various parts of the campus with "what can only be described as human waste." I found proof on Mark's Very Large National Lampoon Site that I'm not crazy... these episodes did exist. You can even find recordings of them on eBay from time to time. I had a cassette tape of the shows, but it has long since deteriorated.