‘World’s Greatest Dad’

The ironically titled “World’s Greatest Dad” is one sick movie.

That’s a compliment.

The latest writing/directing effort from stand-up comic and all-around bizarre character Bobcat Goldthwait is a deadpan black comedy, though one can safely predict that unsuspecting moviegoers who stumble onto it may storm out proclaiming it’s not funny at all.

In one of his best performances, Robin Williams stars as Lance Clayton, a high-school English teacher whose life is one big letdown. More than anything he wants to be a published author, but all he has to show for years of writing is a closet full of rejection letters.

His personal life is a bit better, thanks to his secret affair with a cute art teacher (Alexie Gilmore) who’s half his age. She almost makes up for Lance’s reprobate son, Kyle (Daryl Sabara, all grown up after those “Spy Kids” movies). Kyle is a willfully ignorant, insulting, contrary, gay-baiting teenage jerk who devotes his waking hours to tormenting everyone he encounters, especially Lance.

Without giving away too much, midway through someone dies, and “Dad” turns into a satire that’s savage, sarcastic and insanely brave. After all, making fun of the grief counseling and weepy herd instinct we’ve seen in the wake of real tragedies is going to rub lots of people the wrong way.

But Goldthwait pulls it off. In fact, “World’s Greatest Dad” is one of those rare movies that starts slow and builds in intensity (and discomfort). Stick with it and it’ll send you home feeling practically elated.