Sexlexia
Sexlexia is a "very sexy learning disability." Its existence is brought into question by the fact that Zapp Brannigan is the only known sufferer.
Additional Info
Blackout also suffers from this disease.
Quotes
Leela: You know, Zapp, someone ought to teach you a lesson.
Zapp: If it's a lesson in love, watch out; I suffer from a very sexy learning disability. What do I call it, Kif?
Kif: [sighs] "Sex-lexia".