The NPR story I linked yesterday says that "Animal House" started as a short story by Chris Miller in the National Lampoon (although some characters -- Pinto and Mandy Pepperidge -- made their appearance earlier in Doug Kinney's
High Scool Yearbook in the Lampoon. You can read Miller's story by clicking here:
The Night of the Seven Fires. Enjoy!
P.S. -- I didn't actually read the story until after I posted the link. Not necessarily for the queasy -- and guaranteed to make risk management types unhappy.