During a directing career of just a few features, Bobcat Goldthwait has shown a keen ability to normalize even the edgiest material, using a surprising sensitivity to make the taboo tolerable. He did it in Sleeping Dogs Lie with bestiality, and he does it in World's Greatest Dad with -- well, with a shocking second-act turn of events that's best kept secret, even though many synopses didn't show such restraint. This occurrence changes the film's tone completely, before a third tone emerges that a viewer can scarcely imagine would be possible, given the nature of what happens. Without getting too tangled up in talking about a thing without talking about it, suffice it to say that Goldthwait produces a black comedy that's both very funny, even though the subject matter is no joke, and very touching, all while steering clear of the maudlin misery that might arise from an ordinary treatment of this topic. He has Robin Williams to thank. Stuck in a deep rut of uninspired Hollywood tripe, Williams found his way clear to appearing in this brash and daring independent feature, which rewards both his director, and his own image among people who've grown sick of him. An unassuming schlub who lets life cuff him around, Williams' Lance Clayton takes control in a way that is totally crass, yet somehow laudable. Williams' subtlety as a performer does him a service here, in equal measure to the disservice his lack of subtlety has done him elsewhere. Not only does the viewer refuse to indict Clayton for his otherwise deplorable actions, but the character is effortlessly sympathetic, caught up in a snowballing disaster that stems from a series of small steps across moral lines. That's something with which most viewers can sympathize, making the film's title something more than merely ironic.