I'm sure that the captain would not have been contemplating using anything near TOGA power to get off the grass but to illustrate what can happen: Several years ago at Aberdeen a B734 came off the yellow centreline on lineup to maximise the TODA on the rather short runway. The pilot then held it on the brakes until take-off power was achieved before rolling, unaware that the thrust had dislodged some concrete from the threshold and removed around ten tons of earth and sod. Unfortunately this happened in the dark so the tower ATCO was unaware and the following aircraft didn't remark on what had happened until the B734 was almost airborne. The captain elected to continue to Gatwick even when an airfield inspection revealed a large, six foot deep hole at the end of the runway! On parking up at Gatwick, it was discovered that one side of the tailplane was badly damaged and half of the elevator on that side was missing. Amazingly the crew said the aircraft flew normally with no vibration etc, but it certainly was a lucky day for them and their pax.