Robin Williams isn’t quite convincing as a shouty curmudgeon in the comedy “A Merry Friggin’ Christmas,” but the film’s mix of elements of “National Lampoon’s Christmas Vacation” and “Bad Santa” is amusing.

Williams, who still has a couple more completed films awaiting release, plays a raging dad who consistently ruined Christmas for his son, who grows up to be a wealthy hedge fund manager played by Joel McHale. Obsessed with making Christmas as perfect as possible for his own family in Chicago, the son is instead forced to drive home to Wisconsin to hang out with Mom (Candice Bergen) and Dad on Christmas — only to discover that he left the presents back at his own house. Naturally, father and son wind up driving back to Chicago together overnight, each learning much more about the other than he ever knew.

Director Tristram Shapeero has worked with McHale on “Community,” and the film’s surly humor and oddball characters — like a magical hobo Santa played by Oliver Platt — make the film mostly fun. However, not all of the jokes work, and the comedy does tend toward broad caricature.