Apologies for yet another Daily Mash post but the following was too good to ignore :

The Institute has tracked the origin of ‘meatsock’ to an internet discussion on Gordon Brown, where ‘StevieB1827’ wrote: “Anyone who trusts that boss-eyed fraud can suck my meatsock while my pair of sweaty judelaws bang rhythmically off their chin.”

If that has you puzzled then I suggest trotting over the the Mash to enlighten yourself.