from django.db.models.query import QuerySet

#save original delete method
orrigdelete = QuerySet.delete
def showdelete(self):
    #add on to delete method
    for test in self:
        if isinstance(test, YourObject):
            raise Exception('someone tried to delete your object')
            return  
        else:
            break   
    #call original delete
    return orrigdelete(self)

#set the queryset delete as our new method
QuerySet.delete = showdelete