MTD, or MySpace Transmitted Disease, is something you implicitly have when you are added by a girl with a webcam. They are nasty people, who in all likeliness do not care who they ask to be their freinds, they just want to be "watched". These can also be contracted by people who are added by MySpace whores, aka people with over 200 friends who are not musicians.
"'Hey man, check this out! 'hi! i'm jennifer and i'm kinda new to this, but ur 2 cute!!! i also have a ****free webcam**** check it out!!!!' 'Sick, I can already feel the MTD settling in.'"