Play Challenge mode, and reach the Seeded Pro level. Look at the leaderboard after each hole, and look at your opponents' names. Some of the names listed are references to characters from Futurama, which are as follows:
"Ben B." and "Rodriguez" are references to Bender. "Conrad" is a reference to accountant Hermes Conrad. "Fry" is a reference to Philip J. Fry. "Leeland" is a reference to Leela. "Zoe Berg" is a reference to Dr. Zoidberg.