h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I was once playing with my cousin's Mamod steam engine when the safety valve blew, missing my forehead by about an inch and carrying on up to make a two inch hole in the garage ceiling eight feet above.

Had a similar close escape with a Pressure Cooker safety 25 years later when my kitchen ceiling was coated in stew - Again luckily escaped with no more than a scalded hand.

Oh, and the time I tried to cut my finger end off with the hedgetrimmer [in the days when not only was there only one switch instead of two, you could lock the switch in the 'on' position for convenience!] It didn't actually hurt until I looked at it and saw the flap with blood issuing from underneath. Still makes me cringe!