The Trapalhoes are Brazil's answer to the Three Stooges. They are three bumbling guys who get into a variety of adventures. I only saw a couple of their films while I lived in Brazil for a couple years. In this particular one the bumbling heroes stumble on a tree that when you drink the water around it, you revert to your youth. I think they were running from pirates, but I can't recall for sure. Anyway, the only way to "grow up" is to take a leak (thus passing the magic water out of your veins). So at various times the three "funny" guys get out of various troubles by turning into kids and occasionally whizzing and growing older. If you've got Brazilian kids, they'll probably like it, but the American ones will probably find it pretty stupid, even if it is dubbed.
