An excedingly dull housemate or friend who always ruins the party by complaining about the music being too loud, too many things being spilt etc but also bigs him/herself up as a huge party animal when writing blogs or meeting new people.
"I call a cock up a cock up and not a "contingent operating difficulty which is pompous bollockspeak." -- Tony J. Watson, Organising and managing work: organisational, managerial and strategic behaviour in theory and practice (2nd edition)