Pilot probably just wanted a bit of fun.
In the old days they could stand on the brakes, wind up the power 'till it rattled, dump the brakes and pretend they were being catapulted off a carrier, or else shove a fag packet at the end of the throttles and see how much run-way they could use, or how long they could hold the aircraft off the tarmac on landing for the softest landing, or landing a wheel at a time....
Flyings so booring now for pilots you see....as all flights get fed in to the flight monitoring computer and any issues sorted!!!