The adjective "Ballmouse" originated in Hull University halls of accomodation. During a LAN gaming session, a particular player would often be disadvantaged in the game by their use of a wireless ball mouse - (as opposed to a corded optical mouse)
During a game of Counter-Strike for example, a player may screw up their aim, miss, and get a pummeling from another player. One of the other players then yells "BALLMOUSE!" very loudly within earshot of the player that messed up - and raucous laughter ensues.
The word has since evolved such that it may be called out a someone being self-detrimentally stupid or proving their idiocy to themselves through their ill thought out actions.