When testing out homemade cannons, it's always important to be aware of what is in front of you -- a lesson the MythBusters' guys learned learned last month when their errant cannonball wrecked havoc in a California neighborhood.It is also important, it turns out, to mind your rear. The jolly fellas in this video didn't do that, and when their do-it-yourself heavy artillery backfired -- as DIY heavy artillery will do -- they realized that the rest of the day will be spent doing some light home improvement projects.

Watch a bad decision involving explosion based propellants set to a soothing Johnny Cash soundtrack below.