JOSH Cagan’s adaptation of Kody Keplinger’s novel into a screenplay for Ari Sandel’s debut feature (he has an Oscar for a 22-minute short film) goes to a high-school campus to examine the adolescent practice of the Duff.

No, the film has no pregnant teenagers such as an Australian film with that title might have proposed. A Duff is a Designated Ugly Fat Friend that a group of less-ugly chicks might pal up with so as to appear prettier than she.

In this case, she is Bianca (Mae Whitman), a committed student made up and dressed to look dowdier than she is. Bianca has two chums to whom, for reasons less than convincing, she gives the flick. Bianca likes a soulful boy with low testosterone.

Campus queen Madison (Bella Thorne) personifies the adage about not judging a book by its cover. Bitchy Madison’s relationship with Wesley (Robbie Amell) is on the rocks. Wesley and Bianca become platonic chums.

If from this much information you can’t work out where this is going, “The Duff” may offer a little tension. But not much.

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