Back during my years, the most "creative" use of the spray paint feature Half-Life provided for
Counter-strike was to allow me to drop a "dummy target" on a wall - a custom bitmap of a terrorist or counter-terrorist figure (depending on which team I was playing with) - and wait for blur players to unload their magazines into the equally blur imagery at
point blank range. Me sitting around (in the unseen corner) would then swiftly end their miserable stupidity.
But, with the newer versions featuring in-game team-talk, it looks like someone else has found a
more entertaining use of the spray paint. Albeit less likely to earn better game score.....