1. (noun or verb) a flacid penis, generally long in length, that is difficult to erect. Shaking the penis in attempts to get hard result in a "dead puppet" type motion hence the term floppy sock. Also known as "flop sock".
See Aaron Hands.
Noun - I wanted to bone that bitch but all that Jack I drank gave me a floppy sock.
Verb - I couldn't get it up so I floppy-socked that bitch in the face for a while until I gave up and smoked a blunt.