A highly contagious STD that doesn't necessarily do anything. Once contracted the victim has a highly increased chance of getting dangerous STDs. The Knapp is contracted through any form of penis to vagina contact with any other victim. Side effects of The Knapp are lowered self esteem, occasional mocking, and a significantly reduced chance of ever getting laid again.
Dude, did you hear about Ethan getting The Knapp?
I can't believe Topher has The Knapp