The screams came out of a loudspeaker that looked old enough to be Korean War surplus. Some of the recorded noises were made by gorillas at a zoo, but other blood-curdling shrieks were from creatures of unknown origins, recorded somewhere in the vast woods of the Pacific Northwest.

“I used to have nightmares with this,” Bigfoot researcher John Freitas confessed as he mutes the volume on the amplifier set up in front of the screen in a darkened movie theater.

Freitas said he sets up his speaker out in the forest and plays these noises for days on end “in the hopes of getting a return call, or, better yet, something coming towards us.”

“After playing this for four or five days in a row, that’s all you hear,” Freitas added before playing more grunts at full blast while everyone in attendance covered their ears.

Like the creature that inspires them, Bigfoot conventions are where you find them. I’ve been to Bigfoot conferences held in backyards. This newest one, The Bigfoot Bonanza, is booked for three days at San Francisco's Balboa Theatre, just a few blocks from the ocean.

Along with talks from Sasquatch seekers like Freitas and the cast of Animal Planet’s Finding Bigfoot, the event takes advantage of its venue with repeated showings of The Legend of Boggy Creek (1972) and old In Search Of episodes hosted by a very serious looking Leonard Nimoy.

The Balboa also comes with the perks of hot-buttered popcorn and a liquor license. You can get beer with your Milk Duds if Cherry Coke Zero doesn’t do it for you.

Just about everyone speaking at the Bigfoot Bonanza said they have run into these hairy man-apes during their expeditions to America’s shrinking wild lands, but they’re surprisingly unafraid of the creature.

“I have stopped being afraid of them now,” Cliff Barackman, the man who has taken us on nine seasons worth of Sasquatch hunts on Finding Bigfoot, explained.

“Yeah, when I’m alone and there’s one or two of them around, I do get kind of sketched out, but if that’s the case, I just go to bed.

“Sasquatches are not out to get us,” Barackman added.

Anthropologist Kathy Strain recalled three close encounters with Sasquatches during her trips to find the creature, including one in 2014 with an eight-foot-tall gray beast she described as “probably the biggest thing I’ve ever seen in my life.”

“Were you scared at all?” I asked.

“Not scared at all,” Strain replied. “What’s he going to do?”

“Eight feet tall?” I said, “I’d be scared of an eight-foot-tall human.”

“Eh,” she said, shaking her head. “Once they find my body it’ll have hair on it, or some other form of DNA, so I’m a sacrifice for science.”

James “Bobo” Fay, a fan-favorite on Finding Bigfoot, offers another possible explanation for this fearlessness in the face of Sasquatch.

“Every place we go film, we check out the breweries,” he said.

Bobo likes dark beers like stouts and porters when he’s “squatchin’” in the winter, but switches to pilsners and blonde ales when finding Bigfoot in the summer months.

Bigfoot is elusive at best, and nonexistent at worst, but you can always find beer.

Every month in “Shattering Conventions,” author Bob Calhoun crashes a new tradeshow, convention or conference looking for a way to fit ineven when he doesn't always belong.

Calhoun is the author of "Shattering Conventions: Commerce, Cosplay and Conflict on the Expo Floor." You can follow him on Twitter at @bob_calhoun.