If you’re eager to hear or share a compelling story, the monthly Ann Arbor Moth ­StorySLAM at the Circus bar invites you to participate in an evening of “True Stories Told Live,” the motto of the NYC-based nonprofit behind the now nationwide series. The event’s popularity, both here and elsewhere, suggests it’s more than just a competition or, in our case, a thing to do on a Tuesday night. These genuine, everyday stories are vital and necessary because they represent, according to local StorySLAM host Steve Amick, a “last bastion” against pop culture’s unending barrage of zombies and vampires. So, all those fatigued from staving off the undead, take heart: if storytelling’s a sort of cultural fortress, then ours is a community skillfully and wittily defended by a diverse group of raconteurs.

The StorySLAM takes place in a lighthearted and casual atmosphere (created in part by Circus Bar’s big-top decorations) and is governed by a few loose ground rules. All stories must be real, not fiction, and related to the given theme. Also, every story must be, well, a story. “Something has to happen,” Amick explains; there must be a conflict and resolution. These guidelines are enforced by an amiable, if not tipsy, group of audience members serving as judges, who are allowed to deduct points from a storyteller’s top score of 10 for any violations. In the case of one recent story that seemed more fantasy than reality, though, the judges meted out only a soft penalty. Indeed, the competition seems to be less about winning than it is about encouraging folks to share interesting bits of their lives.

If you’ve attended a live StorySLAM or listened to the show on public radio, you’ve heard a range of Moth stories and know that each is unique in tone, content, and delivery. This kind of storytelling is a genre with fuzzy boundaries, existing somewhere between dinner-table conversation and parable and frequently claiming the stand-up comic’s territory of a well-delivered joke.

It’s difficult to say exactly what makes a winning story, beyond some inscrutable combination of construction, the storyteller’s personality, and other circumstances, such as when during the evening a storyteller is picked to share her story. Of two recent StorySLAM winners, one humorously recounted a series of jobs she held that lacked integrity, including one under a “crazy drunk” boss who loudly accosted Michael Dell, of Dell Inc., at a formal gala. Another month’s winner told comically how he spectacularly botched a swimming race and nearly drowned. Not all the stories are funny, though, nor need be. Part of the evening’s fun and surprise arises from the variety of its offerings.