"Novus ordo seclorum" is Latin for "New order of the ages", and appears on the Great Seal of the United States, printed on the back of the one-dollar bill.
When they go to the fraternity house, there is a toga party going on, with a live band singing 'Shout'. This is a direct reference to the classic 'National Lampoons Animal House' in which the Delta House frat hold a toga party where they hire a live band who perform the same song.