“Hey, Larry Fairy,” Brad Chomner said at school, “think fast.” Which was one of those phrases that never made sense to Laurence: People who told you to “think fast” were always those who thought much more slowly than you did. And they only said it when they were about to do something to contribute to the collective mental inertia. And yet Laurence had never come up with the perfect comeback to “Think fast,” and he wouldn’t have time to say whatever it was, since something unpleasant usually hit him a second later. Laurence had to go clean himself up.

One day, Laurence found some schematics on the internet, which he printed out and reread a hundred times before he started figuring out what they meant. And once he combined them with a solar-battery design that he found buried in an old message-board post, he started to have something. He stole his dad’s old waterproof wristwatch and combined it with some parts he scavenged from a bunch of microwave ovens and cell phones. And a few odds and ends from the electronics store. At the end of all this, he had a working time machine that fit on his wrist.

The device was simple: There was just one small button. Any time you pressed the button, you would jump forward in time two seconds. That was all it could do. There was no way to extend the range or go backwards. Laurence tried filming himself with his webcam and found that when he pressed the button, he did sort of disappear for an eyeblink or two. But you could only use it once in a while, or you got the worst head rush of your life.

A few days later, Brad Chomner said, “Think fast,” and Laurence did think fast. He hit the button on his wrist. The white blob that had been hurtling in his direction landed in front of him with a splat. Everybody looked at Laurence, and at the soggy toilet paper roll melting into the floor tiles, and then back at Laurence. Laurence put his “watch” into sleep mode, meaning it wouldn’t work for anybody else who tinkered with it. But he needn’t have worried—everybody just thought Laurence had ducked, with superhuman reflexes. Mr. Grandison came huffing out of his classroom and asked who threw this toilet paper, and everybody said it was Laurence.

Being able to skip two seconds could be quite useful—if you picked the right two seconds. Like when you’re at the dinner table with your parents and your mom has just said something sarcastic about your dad being passed over for another promotion, and you just know your father is about to let out a brief but lethal burst of resentment. You need godlike timing to pick the exact instant when the barb is being launched. There are a hundred leading indicators: the scent of overcooked casserole, the sensation of the room’s temperature dropping slightly. The ticking of the stove, powering down. You can leave reality behind and reappear for the aftermath.