Whats that teen disease that can be caught by close contact and kissing or even sitting next to eachother?

Mononucleosis: You are probably referring to "mononucleosis" or the "kissing disease". This is an infectious disease common among youth & teenagers caused by a particular virus call the epstein-barr virus. It causes painful swelling of the lymphoid tissue in the back of the throat, "white spots" over the tonsils & throat, swollen glands usually in the back of the neck, fever, tiredness & sometimes a rash.

Mono: Mono (or mononucleosis) is sometimes called "the kissing disease." you can't get it from just sitting next to someone but you can get it from sharing spit. Like sharing the same fork/spoon, drinks, lip balm and .... Yes, kissing too.