my welding/machining/carpentry teacher.
first year, carpentry: "if theres anything i hate more than bent nails, its rust. rust is oxidation of iron and ferrous alloys, and blood contains a lot of oxygen. so heres my warning: if you get blood on my machines, you clean it up before we call an ambulance, otherwise, if the machine hasn't killed you, i will."
in manufacturing the next year: "these lathes have a 2 horsepower motor. i recommend rolling up your sleeves, because if you lose this arm wrestling match, you lose your arm too. and if any blood gets on the machine, ill make the other arm match"
welding, both junior and senior year: "now, you might have heard that it only takes .02 amps to kill you. we weld with anywhere between 50 and 200 amps. this is where i would usually dare you to close the circuit and see for yourself, but last time i said that, i spent two hours scraping charred flesh off the terminals."
stick welding electrodes are numbered in very specific ways so as to be easily distinguishable. in my class we used 6010, 6011, 6013, and 7018 (pronounced with the first two and last two digits as different numbers, e.g. 7018 is "seventy eighteen" ) 6010's and 6011's are about the same, except 6010's are a little more position sensitive, 6013's and 7018's are "fillers" which we use to fill in a deeply penetrating weld made by a 6010 or 6011. 6013 welds look a lot smoother than 6011's so they're generally accepted as a shittier rod (because its harder to tell if you've got a good weld or not, since it smooths itself) and even though they're smooth, they're not as fun to use.
anyway, first day of welding 3-4 and my friend matt was wondering if the teacher would have us start with 6013's again even though we'd been using 6011's most of the last year. he asks the teacher and the teacher tells him we'd be using 6011's matt lets out a sigh of relief and the teacher goes "matt, iv'e seen your welds. even if you were using 6013's, they'd still look like bad 6011's"