About twenty years ago I was helping my mate Adam fix a DIY cockup, he'd fitted laminate flooring in his living room but had fitted it to butt up to the skirting to look nice, of course, as the boards expanded with moisture and heat they bowed up and he realised he needed to leave a gap around the edge and cover it with scotia. Now, he didn't want to take the whole floor up again so his solution was to fit a small circular saw blade to his angle grinder and cut 1cm off around the edge (this is before the days of multitools !). It actually started out working surprisingly well, so whilst he was working I went off to make us a cuppa. Whilst the kettle was boiling I heard a scream and loads of banging and crashing followed by the most terriffying screams and pleading me for help. I ran back to the living room and opened the door to find the angle grinder literally flying around the room tearing holes up the walls, the sofa the floor, the TV unit and Adam cowering behind the sofa. Eventually it cut its own cord and fell to the floor. Adam explained the blade had snagged and ripped the angle grinder out his hand, angle grinders have lock on switches so once he had let go, it just went off on a mental journey of destruction bouncing around his living room, the damage was insane, gauges out the walls 5ft up, sofa torn to shreads in places, the floor was totally F'ed, luckily he didn't have a scratch, could have been much worse !