What's the connection between the words "I hit my head on tofu" and "warning from the past" in Wulin legend?

I had the same problem before, and I finally figured it out after thinking for a long time.

Combined with the plot, Dazui deliberately hit the shopkeeper with tofu in order to pretend to be crazy, but in Xiaoliu's place, he just found fault and had to file a case, but how can tofu be regarded as a murder weapon?

So Xiao Liu quoted that proverb. I don't know whether Xiao Liu really understood the true meaning of that sentence. It doesn't mean to take a warning from Mouth, but to find an excuse to charge Mouth.

Past warnings mean nothing. On the surface, Xiao Liu seems to be warning himself that "someone once committed suicide on tofu, which is a lesson from the past." In fact, it is purely an official idiom used by Xiao Liu. Later, when examining the shopkeeper in the hut, Liu Ye Jr. burst out with "What a pity ~". Then the exhibition hall also laughed at Xiao Liu's ability to use idioms, but Xiao Liu couldn't read or even read.

It's like in a certain era, everyone went to the countryside to do farm work, and then this group of people would give intellectuals a necessary charge on the grounds of "breaking away from the masses, violating mks and opposing socialism".