How to make the weakest bomb (that still explodes)

[atomic1fire]

Most people, when researching bombs, go for high power, stuns, effects and other harmful stuff, but what if I just wanna goof off and prank engineering with a can bomb that only damages the tile below it? I wanna know the WEAKEST most ABSOLUTELY USELESS bombs you can possibly make (No butt bombs don't count, those are awesome, anyone who disagrees is a dirty heretic and shall be spaced instantly)

Just throw stabilized smoke powder in a beaker, attach an radio signaller/igniter to it and then hide it behind a bush somewhere. Mix with carbon for a bomb that just shoots dirt everywhere.