The repetitive snap-back jerking movement a vehicle makes when its driver reflexively returns momentary attention to the steering wheel while simultaneously text-messaging and driving, narrowly avoiding a ditch, then a parked car and finally a pedestrian.
Derived from "texting" and "jerking".
"Do you see that terking menace? I thought the driver was having an epileptic seizure until I saw him engrossed in his cell phone."
"Whoa, get out of this lane. Terker on your left."