更正一下,是五秒定律
https://en.wikipedia.org/wiki/Five-second_rule
In folklore, the five-second rule states that food (or sometimes cutlery) dropped on the ground will not be significantly contaminated with bacteria if it is picked up within five seconds of being dropped. 意思:民间传说,食物或餐具掉地上五秒内捡起来是不会明显地被污染,变脏的。(所以吹一吹就可以吃了)