Sexlexia is a learning disorder that Zapp Brannigan claims to have, which prevents him from being taught lessons of an intimate nature. While it is possible that Zapp has made up this condition, his track record seems to indicate that he has problems with his love life, and so it is likely that he does suffer from an affliction but has chosen to rename his disability for his own reason, possibly implying that he has Dyslexia.