So one twin fetches the drinks, telling the counter girl that "her dad" will pay for them when he gets out of the bathroom. She carries the diet drinks over to a table and pours some digitalis into each of them, finishing just as Mulder shows up. She tells him that the drinks on the table are his and Scully's. He takes a sip. "These are really sweet," he says, holding the drink towards her. "Try it." The twin shakes her head. "I know it's diet, I saw her pour it," she chirps. "Okay," Mulder says cheerfully. The twin reminds him not to forget the other drinks, so the two of them go to the counter. Mulder nicely lets the twin complete the transaction, because, you know, kids like to pay. He grabs the other drinks and meets Scully and the other twin at the door. Mulder hands Scully her drink.
The four of them head out to the car. Scully takes a sip of her drink. "Tastes syrupy," she says. Mulder pats his pockets and realizes that he's forgotten his keys. Scully and the evil, evil, evil twins wait for him by the car. "This is what it would be like if Mulder and I were married," Scully thinks dreamily. "Drinking poisoned sodas at a truck stop by the side of a highway, unaware that our incredibly intelligent, super-strong children are trying to kill us."
Mulder finds his keys on the table where the drinks were. Right next to a suspicious ring of green powder. Mulder runs his finger over the powder, and smells it. He sticks his finger in his mouth. A light bulb goes on over his head and he races outside, calling Scully's name. "What?" she asks, looking up from her daydream. He races over to her side and grabs her elbow. "I just wanted open the car door for you," he says, taking her over to the other side of the car. Scully looks at him, like, okay, freakshow. Mulder knocks her drink out of her hand. "It's them, Scully," he hisses. "They poisoned the drinks." Behind them, the girls exchange a look. When Mulder and Scully glance toward them, they're nowhere to be seen. "We didn't drink enough to make us sick," Scully says, as she and Mulder draw their weapons and start to search the parking lot, which is full of eighteen-wheelers. They weave in and out of the trucks. Trucks. Mud. Trucks. Mud. Trucks.
Eventually, Mulder catches the twins, and manages to grab both of them. They start screaming for help, attracting the attention of a trucker, who climbs out of his cab and pulls his shotgun on Mulder, ordering Mulder to let the girls go. His wife, coming out of the truck behind him, threatens to "call the cops." Scully comes running up. "We are the cops," she says. The Trucker and Mrs. Trucker roll their eyes. Mulder reluctantly lets the girls go. They run off again, natch. Mulder and Scully take off after them, this time flashing their badges at the trucker couple, who look at each other like, "Whoops."