The Centre Daily Times reports that the assault happened Saturday, the night the Nittany Lions defeated the rival Wolverines 41-31.
Police say the men attacked the fan because they thought the colors of his costume indicated he was a Michigan fan. Michigan's colors are blue and yellow.
The attackers have not been identified.
Police say the victim sustained a possible broken nose and was treated and released from a hospital.
Information from: Centre Daily Times, http://www.centredaily.com