the distance of one cigarette
Sanji measures time by cigarettes. He measures hours and distances. For example, he smokes approximately seven sticks a day and there are twenty sticks in a pack, and he'd gone through a pack and a half on the way to roguetown from arlong park - so, counting the day he only smoked three cigarettes because he woke up coughing and that was bad luck, he figured the sea journey took them five days. And he was correct.
And again, there was this one time when he realized it had been a little over one hundred packs since he last saw the old man. It's high time for a frickin' anniversary, he said to himself. He thought about not smoking for a day to mark the occasion, but he was afraid of stopping, because if he ever lost track, he might never be able to find his way back to where the old man lived, and he didn't want to risk that.
He relies on his cigarettes, because clocks and compasses sometimes lie, and calendars are different everywhere, and you need to have something with you that won't let you down. Since it's impossible to measure with breaths, he thinks, or heartbeats, you settle for the next best thing.
Sometimes, of course, he has to stop because he runs out. It's not easy to get his favorite brand because not all the ports carry them. And if he smokes too much and fails to keep himself in check, he has to go without a stick for days on end, which is the worst thing about being in a small ship with a bunch of mental patients who can't pass up the opportunity to make his bad mood worse.
He counts the "dry" times, too, the absence of relief. It's still a way to mark the hours, the distance between one cigarette and the next. In the end, it goes with the reckoning. It's still easier to keep track of the days by counting the number of butts in an ashtray, than by trying to recall the number of sunrises and sunsets you've survived.
And he doesn't smoke when he's having sex, either, but the temptation isn't exactly there. There's no sense in counting time when you're having fun. Sometimes he forgets to light a stick when he's cooking, but you really shouldn't smoke when you cook anyway, lest the ashes fall into the pan or onto the plate. (Sanji knows this. He only picked up the habit of smoking in front of the stove to spite the people who told him he shouldn't do it in the first place.)
Sanji has noticed something peculiar... after bedding women, it takes him three cigarettes before he either falls asleep or is ready for another round. On the other hand, after bedding Roronoa Zoro, it takes him five cigarettes. Which is almost as much as he burns up in a day. It may be because the moron goes right back to sleep afterwards, or because Sanji finds himself thinking of things he normally wouldn't think about, and time goes faster, in step with the workings of his brain.
Then Zoro would wake up, or Sanji would get tired of thinking, and then.
And then... five more cigarettes.
Bastard's going to kill me, Sanji thinks, running the tips of his fingers lightly over the ends of Zoro's hair. He can only do this for a breath, the moment when the smoke fills his lungs, because if he takes longer, the idiot will stir, thinking he's being assaulted. Or worse, he won't, but he'll see anyway and all throughout the four cigarettes before dawn, annoy and heckle Sanji for going sappy on him.
One of the things that Sanji thinks about during those five-stick times is, when did he start counting the days between the nights he spends with Zoro like cigarettes? When did it start being not okay to not lie beside him like this, when did the daylight become like the absence of relief, between one stick and the next?