A series of flashbacks reveal that Zoidberg first met and befriended Farnsworth in 2927, during a mission to kill a Tritonian yeti for Mom.
Farnsworth now fears that he has contracted hyper-malaria, a painful, fatal, incurable disease which can either strike instantly or remain dormant for years.
Zoidberg notices a single white hair on the Professor's coat and deduces that he does not have hyper-malaria, but rather yetiism, which he had contracted after having been scratched by the Tritonian yeti.
Mom, who has great respect and admiration for Zoidberg, says that he is "the best in the business" when it comes to alien anatomy and asks him why he stayed with the Professor all these years instead of opening his own research lab and becoming very wealthy.
Zoidberg is unable to pay for the yeti head, but Mom accepts payment with the only thing he has – a coupon for a free tanning session.