Overloading
I'm surprised to hear a professional?? pilot blithely talking about taking off above MTOW. The figure is there for a reason, determined by the designers and engineers who built the thing. Flying outside the figures, performance/weight/whatever, listed in the manual means you're in territory which no flight/component testing has guaranteed.
In any case, succeed, and you saved, what, money/time/reputation??, although you might quite possibly kill the next poor bloke who has to fly the aircraft, fail and you kill yourself and your passengers.
Dave (the bloke who pushes above the limits due to his 'experience') is always wrong.