In a post-“Bridesmaids” world, the ensuing wave of gross-out films starring female leads is inevitably starting to wash up into theaters. In the summer of 2011, “Bridesmaids” snuggled up to the stereotype that women aren’t funny – or at least not in the same way as men – and beat it to a pulp. The film’s inspired, hilarious weirdness gave that particular adage two black eyes and a neck brace. The nearly $300 million worldwide box office suggested that it was lightning in a bottle, but executives’ eyes lit up with dollar bill signs, as if out of an old Looney Tunes cartoon. Kristen Wiig was immediately deemed a movie star (the jury’s still out) and Melissa McCarthy was nominated for an Oscar. It’s hard to blame Hollywood for getting over-excited.

“For A Good Time, Call…” is one of the first films to follow in the wake of “Bridesmaids,” following the Apatow model of “50% raunchy, 50% sweet.” What it doesn’t have, however, is a sharp screenplay or any sense of what to do with its characters. It has nothing in particular to say, apart from reheated comments on the nature of friendship (which “Bridesmaids” did much better) and the first half of the film isn’t very funny. When the funniest scene in a comedy is a sight gag involving Kevin Smith, you might be in dangerous waters.

Fortunately, co-lead Ari Graynor gives the sort of breakout performance that the film requires. She stars as Katie, the quintessential mid-20s party girl who secretly makes a living as a phone sex operator. Her reluctant roommate (the two have a bad history), the tightly wound Lauren (played by co-writer Lauren Anne Miller), has no choice but to live with Katie because neither can afford rent in their neighborhood. Lauren finds out about Katie’s business and becomes intrigued, slowly becoming involved. The phone sex angle is unusual because there’s very little sexual content onscreen, but the language is very graphic and the R-rating is well-deserved.

Graynor owns every scene she’s in, while Miller (Seth Rogen’s real-life fiancée – yes, he makes a cameo) is uninteresting and lacks any discernable screen presence. What makes Katie so appealing is that there’s more to her character than we initially think, which is revealed methodically over the course of the film. Graynor possesses a go-for-broke sensibility that allows the audience to really connect with her and she has a masterful grip on the line between airhead and genius. Lauren’s far-fetched transformation doesn’t ring true and only muddies the message of the film.

Justin Long plays the mutual friend that re-introduces the pair and he’s classically misused. Given the right material, Long can be very funny, but when given free reign and far too much screen time, it’s a chore to watch him. It’s a very broad role – the character is essentially an excuse for a tornado of gay jokes – and he’s borderline cringe-inducing at times. Mark Webber is on hand as Katie’s love interest, Sean, which might be more palatable if he wasn’t a customer of hers. It’s an uncomfortable dynamic and the filmmakers made an even stranger choice in playing it ambiguously.

“For A Good Time, Call…” is an adequate comedy for grown-ups, mostly because Ari Graynor’s performance is too likable to dismiss the film as a whole. Other than ramping up the filthiness within its genre, the film doesn’t break any new ground, but it’s occasionally funny and charming and probably worth a matinee if you like your chick flicks as profane as possible. To call a movie “airy” and “slight” is a backhanded compliment at best, but in reference to such an inconsequential and inconsistent piece, “not bad” is as much of an endorsement as I can give it.