Owning rental property I had enough "never do again" for example working on a live Breaker box and rubbing a ground wire on the hot, produces a nice big bang and your pants get crapped.
Other things like taking the battery out of a drill after using it, otherwise have the trigger depressed on some tool and drill out your work bag.
Penetrating blaster works great unless you throw a cigarette down next to a lawnmower then use PB to loosen up the blades to take them off - and hit the cigarette causing the entire bottom of your deck to catch fire.
Never stick a handful of self starting 1.5 inch nails in your back pocket, because if you forget about them and sit down, you might have a nasty gash on your ass.
Lets see, Degreaser on the hands isn't much of a problem anymore, one little paper cut and degreaser causes extreme pain - normally wear gloves but forget about it half the time.
Poison for the septic tank is a fun novel, never stick your face RIGHT over the pipe while running hot water (since it activates the drain cleaner) you get knocked out in 2 seconds and pass out.
Weed killer (the real stuff used by CSX) works great unless your sprayer trigger gets depressed while you are riding around the property (Being in a trailer attached to a lawnmower) - all the grass from point A to point B gets killed.
Lets not forget about filling the small trailer behind the lawnmower with trash and hitting a bump and have it flip over spewing garbage all over the place.
Could probably think up another 100, but these are just off top of my head within last 6 months heh. I did have one good catch though, recently filled my fire extinguishers up (licensed to do so) and had a guy who broke down on the main road at night time, was out side having a beer when I seen flashes drop from his engine - I picked up one of the extinguishers and ran over telling him to get out of the truck - the guy was COMPLETELY clueless - my biggest mistake was telling him to open the hood, it should of probably exploded on me, but soon as the hood lifted flames just spew every where.
Got the fire out, although the guy wasn't to bright - I called fire department to make sure everything was out - in the mean time he's busy calling buddies on how to "repair" the damage so he can drive off. Yeah, pretty sure every wire in that engine compartment was gone at this point.
Two hours later he finally calls a tow truck, never even bothered to say thanks - jerk.
