Independent bookstores are the best. You never know when you're going to have a profound experience browsing the shelves, an encounter with a famous writer, or an unexpected flirtation with someone who has the same taste in books as you do.

On April 29, nineteen Seattle-area bookstores are participating in Independent Bookstore Day. If you visit all of them and get your Indie Bookstore Challenge passport stamped at each, you get 25 percent off at all those stores for a year.

Two years ago, 42 people completed the challenge; last year, 120 people did; this year, maybe you?

In anticipation of Independent Bookstore Day, I visited a few of the participating bookstores and put their staff members on the spot: What's the craziest thing that's happened in their store?

Elliott Bay Book Company

1521 10th Ave, 206-624-6600

When international literary star Karl Ove Knausgaard came to the United States with the first volume of his six-volume memoir, My Struggle, he visited two cities: Seattle and New York City. It just so happened that one-of-a-kind memoirist Geoff Dyer (Out of Sheer Rage) was in town doing an event at Benaroya Hall the same night and wanted to meet Knausgaard, so he came up to Elliott Bay. It also just so happened that David Shields, another one-of-a-kind memoirist (Other People), was following Dyer around like a fanboy that night. An Elliott Bay employee remembered the moment as "three of the most self-obsessed, self-referential writers on the planet" converged in one place. He also remembered Knausgaard was "smoking every moment he could," and that afterward they all went out to Oddfellows for beers and left hastily. Months later, Dyer apologized to Elliott Bay's Rick Simonson: "I realize we ran off and stiffed you on the beer."

University Book Store

4326 University Way NE, 206-634-3400

This one is a three-way tie between the woman who camped outside overnight wearing a panda suit while waiting to meet Hillary Clinton, the little boy who came to a Cary Elwes appearance dressed as Dread Pirate Roberts from The Princess Bride, and the time Alison Bechdel signed the bras and panties of a gaggle of young women.

As for the woman in the panda suit: "She wasn't allowed to wear the suit to meet Clinton, and, by the time of the signing, employees had stashed the suit behind the sales counter," The Stranger reported at the time, in 2014.

The boy dressed as Cary Elwes in The Princess Bride got lifted into the air by Elwes, while everyone in the store snapped pictures.

And as for the Bechdel incident, the fans in question were "super cool, very attractive," according to manager Pam Cady. "They waited for everyone else to leave. [Bechdel] had never [signed underwear] before, and she was like, 'Really? Okay!' She felt like a rock star, and to us was a rock star."

Third Place Books

17171 Bothell Way NE, Lake Forest Park, 206-366-3333

Events manager Wendy Ceballos recalls booking John Irving and Hulk Hogan on the same night. The Lake Forest Park location is big enough to do multiple events at once, so they do it sometimes, but this was a particularly interesting pairing. "John Irving was onstage and had like 200 people, and Hulk Hogan had a signing line only. The audiences couldn't be more different from each other, and they were sort of bumping into each other. And I got them in the back room, and of course John Irving knew who Hulk Hogan was, and Hulk Hogan had no idea who John Irving was," Ceballos said.

Seattle Mystery Bookstore

117 Cherry St, 206-587-5737

"We do have a ghost," one employee said when I asked if there was anything mysterious about the store. "About 15 years ago, one of the staff came out from the back hallway and asked her colleague if the man back there had been helped. Her colleague told her there was nobody back there. When they looked, there was indeed nobody back there. The woman who saw the man described him as a dark figure wearing a long overcoat and a funny round hat. And a few months later, a guy came in who said that his great-grandfather had had a barbershop in our space back in the time of the Alaska-Yukon-Pacific Exposition in 1909, and the next time he was in he'd bring us pictures. The next time he came in, weeks later, he brought a picture of this space when it was a barbershop and a picture of his great grandfather, who was wearing a long dark overcoat and a bowler hat. The woman who had been working and had seen the dark figure didn't know the term for a bowler hat." He paused to let that sink in. "And occasionally books fly off shelves. We usually say, 'Hello, ghost.' And two women who work here with me now occasionally feel someone futzing with the hair on the back of their head. That's when they know it's time for a haircut."

Eagle Harbor Books

157 Winslow Way E, Bainbridge Island, 206-842-5332

There are no ghosts at Eagle Harbor on Bainbridge Island, although the booksellers do seem to have a psychic connection to their customers. "We will often order books for customers before they know they want them," one bookseller told me. "We know our customers better than Amazon. Our algorithm is us." When the book arrives, they'll call the regular they have in mind and say: "We have a book you might like..." And they're almost always right. Also, a bookseller once fell in love with one of the customers, and now that bookseller owns the store and she and that customer are married.

Phinney Books

7405 Greenwood Ave N, 206-297-2665

An employee laughed when I asked for the funniest story, and talked about how the great thing about a small store like this is the low-key charm of neighborhood regulars, and then remembered something unforgettable a regular told him. This regular is a delightful woman in her 80s or 90s, "still glamorous," who comes in all the time, sometimes with her small dog. She was making small talk at the counter when she said, unexpectedly, "Not many people know this, but I dated Shel Silverstein from 1972 to 1975, when he lived at the Playboy Mansion."

Secret Garden Books

2214 NW Market St, 206-789-5006

"We took Stephenie Meyer on her first school visit ever, right at the time Twilight was being published," a bookseller at Ballard's children's bookstore recalled. The store has "tinkle bricks" in the pavement outside that make noise when kids walk on them. "You walk, and as you move, they make sounds. Toddlers love them. You don't have to weigh more than 30 pounds. I swear to God, after that school visit, I was walking on the tinkle bricks, and I looked down and I said: 'Stephenie, the bricks aren't making any sound.' I'm not making this up. I said, 'Stephenie, why are the bricks not making any sound?' Like she's a goddamn vampire! Once I brought it to her attention"—once the vampire was alerted to the effect she was having—"they started tinkling again."

Fantagraphics Books

1201 Vale St, 206-524-1967

This comics store is right in the heart of Georgetown, near a bunch of bars and Pearl Jam's practice space. "We frequently have customers who'll recognize one of the guys," one employee said. "We also frequently have inebriated customers walking around looking for the bar. I like that. If they're inebriated enough, sometimes I can sell them a few comic books before I direct them around the corner to 9lb Hammer." As for crazy stories, Larry Reid racked his brain and said, "I think one of the funniest things that happened in recent memory was a patron who spent about half an hour perusing the store and then came up to me, mystified, and asked: What kind of store is this?"

The other stores participating in Independent Bookstore Day are Ada's Technical Books (425 15th Ave E), Book Larder (4252 Fremont Ave N), BookTree Kirkland (609 Market St, Kirkland), Edmonds Bookshop (111 Fifth Ave S, Edmonds), Island Books (3014 78th Ave SE, Mercer Island), Magnolia's Bookstore (3206 W McGraw St), The Neverending Bookshop (10123 Main Pl #2, Bothell), Open Books: A Poem Emporium (2414 N 45th St), Queen Anne Book Company (1811 Queen Anne Ave N), The Traveler (256 Winslow Way E, Bainbridge Island), and Liberty Bay Books (409 Pacific Ave, Bremerton). For more info, go to facebook.com/SEABookstoreDay or @SeaBookstoreDay on Instagram and Twitter.