Read about the United 737 runway excursion in KDEN about using rudder inputs on the runway. At high speed bad things can happen. At really low speeds, with an engine failure or one engine not spooling up, it's a quick way to turn approx. 60 degrees to the runway heading.
Hideous to watch, nose of the aircraft bouncing up and down as the tires gain, and then lose, traction with smoke pouring off of the tires.
If you see big skid marks starting at the runway centerline, at the departure end of the runway, and curving towards the side of the runway and then back towards the centerline, you're looking at the evidence of an uneven engine acceleration on takeoff beyond the nose wheels ability to maintain directional control.