1) A type of lunch meat.
2) An unsolicited and usually annoying email usually reserved for advertising.
3) Gaming #1: the overuse of any weapon (i.e. grenades, rocket launchers, etc.)
4) Gaming #2: in RTS (real time strategy) games, to mass produce a certain unit (usually only one or two--especially used with over powered weapons) to use in a quick, game-winning assault.
I really hate playing against John--he does nothing but sit back in his base (often called turtling) and spam out two dozen tanks that kills anything in their path.