The distinction between organic and inorganic carbon compounds, while useful in organizing the vast subject of chemistry... is somewhat arbitrary. Organic chemistry is the science concerned with all aspects of organic compounds. Organic synthesis is the methodology of their preparation.
No, it is not possible to contract the typical STDs, such as syphilis, gonorrhea, chlamydia, hepatitis B, etc. from wearing someone else's dirty underwear. However crabs and scabies, may be spread in this fashion.
Long says they tested the theory by having men and women have sex with people who were positively infected with genital herpes, Gonorrhea, crabs, and syphilis. Of the 50 men and 50 women who were exposed via unprotected sex during the study, all were told to continue until climax, and then immediately shower.