Acronym for 'fuck me dead', often used when abbreviating in text messages, online messenger systems or social networking services such as Facebook, Myspace and so on.
example 1:
girl #1 "fmd, that boy is hot!"
girl #2 "yeah, i'd let him fmd!"
example 2:
boy "this really hot chick invited me to a party tonight, but i have to work. fmd."