There is no doubt that it is Think Big. My brother and I quote this all time along with several other one-liners from this movie. Yes, it was horrible, but was funny nonetheless. And remember, the brothers are not two big dumb guys, they are two HUGE dumb guys!
The movie is "Think Big" from 1990. If I remember correctly, the movie was so bad it was actually kinda funny.
I can't quite remember the whole thing but I think it was "think big" with the barbarian brothers