Two people lie on their backs facing in opposite directions with their arms stretched above their heads, while two other people lie face down on top placing their arms above their heads and onto the floor. When each persons genitals are matched to another persons face this makes a tic tac toe shape or 'octothorpe'.
An idler who in the lobby all day waiting for someone who beats him to log on so that person can be called a cheater/quitter.
A forum troll who likes to complain about everything and nothing because he has no life/job.
A noob who makes plats no matter the map. His motto, "the bigger the map, the more plats I attack with."
(2) medical: Brain abscess
(3) legal: act of being online to find little friends wanting to visit one's porn site
3 - He was arrested for octothorpe