Function: noun; vulgar; Method: The act of fellating (performing a blowjob on) a distended or inside-out rectum (commonly referred to as a pink sock or a red sock).
Someone (usually a guy) who talks big about things to make themself look better. What he can do, buy, etc. Usually what they are saying is not true at all, or it's a very large exaggeration of the truth.
James was being such a blowcock again, ranting about how many women he's been with and what type of car he drives.