There is a saying that "two people don't light a fire, three people don't light a cigarette". The first half of this proverb means that when two people are smoking, they should not use another cigarette to light a lit cigarette, but should use a lighter or match to light it. All smokers should know this kind of attention, and generally don't do it, mainly because it is a very impolite behavior, just like a person inviting you to dinner and giving you his used chopsticks.
It's not only impolite to do this, but also like smoking other people's cigarettes, which makes people feel unsanitary. But if two people have a good relationship, it doesn't matter if they don't care. But there is a superstition among the people that two people are not good for cigarettes and their wives. Because of this explanation, this proverb was almost abandoned as superstition, but it was later clarified, just to prevent people from deliberately exaggerating cigarettes. It's complete nonsense, and everyone has misunderstood it, so this proverb is not superstitious.
The second half of this proverb "three people don't light cigarettes" means that when three people smoke together, they can't light three cigarettes at the same time. You know, you used to light a cigarette with matches. If you order three at a time, the third person may not be completely lit, which will make people feel that the lighter person does not respect him, so it is best to order two or three times. Even if no one uses matches now, it's better to hit the lighter when lighting someone else's cigarette. This is respect for people.
If you hit a lighter once and light a cigarette for a person, it won't make others think that you regard a person with special respect. At first, this sentence was completely abandoned because it was not good for your daughter-in-law, but it has been used since then. Basically all smokers know this unwritten rule. Do friends who smoke know this sentence?