In the beginning of the story
Like Water For Chocolate, the
author writes: "Take care to chop the onion fine. To keep from crying when you chop it (which is so annoying!), I suggest you place a little bit on your head. The trouble with crying over an onion is that once the chopping gets you started and the tears begin to well up, the next thing you know you just can't stop. I don't know whether that's ever happened to you, but I have to confess it's happened to me, many times. Mama used to say it was because I was especially sensitive to onions, like my great-aunt, Tita." (Page 1)
I found the suggestion of
placing a little bit on your head, interesting... Whenever I hear
various "methods" of ways-to-not-cry-when-cutting-onion (lighting a candle, tongue to roof of your mouth, wear goggles, chew gum, etc...), I never know if they actually are real techniques, or if someone just made it up.
Personally, because of the saying, I don't usually offer to cut onions. The few times I have cut onions, my eyes got a little teary eyed. The most important lesson I learned in my high school Food and Nutrition class was: "Never rub your eyes when you are cutting / holding onion."