More ways to measure a second. Wheel721 suggests the second could be defined as

“the time it takes for a 16 year old boy to cum after slipping his dick into his first pussy.”

Emma turns off the sink water, having finished the dinner dishes, and she hears the thump, thump, thump. For a moment she thinks it is the grandfather clock. The interval between thumps is so regular, about one second each. But that grandfather clock hasn’t ticked since the cat leapt on it almost a year ago. Emma dries her hands and steps across the kitchen and down the hall. In the living room, sure enough, the grandfather clock still slumbers. Alina’s bedroom door is open a crack. The thumping is definitely coming from in there. Louder. Thump, thump, thump, each a second apart. And each punctuated by a soft, sweet squeak. Emma knows that sound. It is the whimper Alina makes when she was being fucked, when she is a minute or two from orgasm. Emma eases the door open. Sure enough, there is Alina, up against the wall, and there is Nils, fucking her. Emma watches them. Nils hips driving forward. Pulling back. The gleam of sex juice on Nils’ big cock as it pulls almost but not quite all the way out of Alina’s cunt. The thump as Nils fucks forward, pushing Alina’s shoulders against the wall. Alina’s soft, sweet squeak. It won’t be long now. Another ten or twelve thumps should do it.