On the subject of hilarious sports rivalries, my personal favorite at the moment is the rift between my college and its hated and despised rival, which dates from roughly 1824(1) and has continued with unabated, NCAA-alarming fervor(2) in the adjoining 180 years.
Both my school and its rival are named after colonial figures somehow involved in their inceptions, and in typical uncreative fashion, both have as their mascots the same colonial figures. Thus, we have the eternal rivalry between the Ephs(3) and the Lord Jeffs. I'm surprised our football teams haven't started showing up with bayonets and muskets.
(1) The man who would become Their president was originally one of Our professors; he decided that We were too remote and, with suitable gravitas and respect, he stole half of Our students and half of Our library books before running off to become Them. We send them overdue slips ever so often, but no dice.
(2) This got to the point that, during the Division III basketball playoffs, we got an all-campus e-mail begging those of us who went to the game to please not yell personal insults at Their forwards and that people wearing the "what do They and shit have in common" T-shirts sold at Homecoming would be ejected from the gym. Go Us.
(3) Short for Colonel Ephraim. No connection to matchsticks and doody, as far as I know.