A quick googling finds this: http://poker.about.com/od/pokerglossary/g/bubble.htm It makes sense to me that it would arise from poker as the game is so popular right now, and has been for the last 5 years or so, especially Texas Hold'em. It may stem from, as tsuwm said, rolling easily in any direction, indicating an uncertain outcome. To me it indicates the perilous position of someone, or something, that if it goes the wrong way, the bubble will break and somethin's gonna fall! It could also relate to being on the edge, as that's to where bubbles usually migrate, still indicating a risky position. :0)