STDs

A young couple that's been dating have been getting on pretty well, and so the time has come to make love for the first time.  They're in the bedroom ready to undress.  The young man removes his shoes and socks.  His partner sees his feet and exclaims, "Your feet!  My God, what happened to your feet?!"

"Oh," he says.  "I had a case of Toelio."

He continues undressing and removes his pants.  When she sees his legs she exclaims, "Your legs!  What happened to your legs?!"

"I had the Kneesels."

He continues undressing.  As he removes his underwear, his lady friend says, "Oh no.  Don't tell me.  Small Cox."