Syphilis
From Gomerpedia
Syphilis is a... a... well, let's just say you don't want to catch syphilis.
Latent Syphilis
Shhhhh!!!! The syphilis is sleeeeeping. (Be quiet, you don't want to wake it up.)
Primary Syphilis
When you catch syphilis the first time. Beware the chancre, which is cancer misspelled with an H mixed in.
Secondary Syphilis
When you catch syphilis twice! DRATS!!! Sometimes the second syphilis can manifest as a rash (see Maculopapular Rash).
Tertiary Syphilis
Damn it, you've caught syphilis for a third time! An unfortunate complication is neurosyphilis, a condition where your neurologist catches it from you.
Treatment
Penicillin. And stop sleeping around. Safe sex, people, safe sex!