"Marriage is like sticking your tongue on a frozen flagpole," explains Reverend Frank (Robin Williams) at the start of the limp comedy "License to Wed." It's a vivid if off-putting metaphor — people get married, he explains, because they see everyone else doing it and it looks like fun, and then they get trapped — but it's actually better suited to the experience of watching the movie itself. "License to Wed" is sort of a frozen flagpole of a movie, and sitting through it is a painful reminder of all the better things you could be doing (i.e., watching "Ratatouille," doing errands, having unpleasant dental work done ... ) if you weren't stuck right there in that theater seat, watching Robin Williams do his best to make us forget that he was once off-the-leash funny.

Ken Kwapis, a filmmaker whose uneven résumé includes "The Sisterhood of the Traveling Pants" and "Dunston Checks In," brings little zip to the material, which gets less and less funny as the movie plods endlessly on. Sadie (Mandy Moore) and Ben (John Krasinski) are a sparkly-eyed young couple who meet, fall in love, and get engaged with a minimum of fuss. Enter Reverend Frank, Sadie's childhood minister, who insists that they complete his marriage-preparation course before the big day.

Sound funny? Well, it's not, even when you find out that the Reverend is a bit of a nutjob whose course includes spying on Sadie and Ben's bedroom activities (thanks to a bug planted in their apartment by Frank's preteen henchman), making Sadie drive a car blindfolded with a frantic Ben guiding her, and forcing the two of them to take care of a pair of creepy robot babies whose nether regions spurt blue goo.

Williams zooms around trying to keep the energy level up, but the screenplay repeatedly strands him, and there's little of the wildly improvised (or seemingly improvised) comic shtick that he employed to good effect years ago. (Has Williams been genuinely funny in a live-action film since "The Birdcage," more than a decade ago? Maybe he should stick to the creepy dramatic roles he does so well, such as in "Insomnia" and "One Hour Photo").

A few supporting players register in small roles: Bob Balaban as an officious jewelry salesman, Wanda Sykes as a hilariously sadistic nurse, Grace Zabriskie as Sadie's dour grandma (who spends the film looking huffily disapproving, as well she might). But Moore and Krasinski, though likable, can't find anything distinctive in their underwritten characters. Like some weddings, "License to Wed" is a long sit and a bland buffet.

Moira Macdonald: 206-464-2725 or mmacdonald@seattletimes.com