How long was the runway?
With an extra 10 tons, it's not just the change in centre of gravity that they should have been worried about. I just went in to the the performance chart for a B737-800 with 24K engines and 10 tons equated to an extra 900 metres of take-off distance required!
Maybe there was a tail scrape because they were desperate to get the thing airborne as the end of the runway was rapidly approaching and they...
Actually on second thought, I think the whole idea of the captain deliberately taking off with an overload of ten tons is just not believable. I just can't believe it!
But then again...
http://www.youtube.com/watch?v=aWtdtuspnoM