Bok, a gambling term for someone who's bad luck, the favourite origins of this are a bloke called Yakob Bok (I think) a really unlucky bloke in the novel The Fixer or from the Turkish word for shit
I don't want to be a miserable but I always found him to be a bok, if we were doing ok in a vital World Cup match he'd always compare it to something that went badly wrong which we ended up losing (West Germany 1970 and 1990, Poland 1973 etc etc) and right on cue we'd end up losing