I don't know if they still do it, but for many years, the University of Chicago's Blackfriars sacrificed a watermelon on Walpurgis night. The abbot or abbess would plunge a knife into the unfortunate mellon, after which, the victim would be eaten.
Blackfriars is a highly subversive organization, they perform musicals. Milton Friedman used to be one of their favorite targets for satire.