WATCH: Flash Mob Hands Out Flowers for a Super-Sweet Marriage Proposal

When Jack Cushman decided to propose to Teresa Elsey, his girlfriend of several years, he was certain that she'd say yes. So all that was left to figure out was how he'd make the moment memorable.

"Since I wasn't too nervous about the question itself, I decided to come up with a ridiculously complicated plan to worry about instead," Cushman wrote in an essay for The Huffington Post. "When she suggested a date to the Institute of Contemporary Art (ICA), where we'd gone on our first date, it seemed like the perfect time."

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He enlisted his best friend and his brothers to help him pull off the proposal.

"They've been together for so long that it wasn't surprising that they were getting married, but he wanted to do it in as surprising way as possible," his friend Ben Pender-Cudlip, a documentary filmmaker and the founder of Unrendered Films, told Yahoo! Shine in an interview.

Inspired by a music video project they'd worked on together, Cushman decided to organize hundreds of strangers into a flash mob to give his girlfriend 300 pink and white flowers as they walked from her office to the museum on August 2. And he had his film making friends document the whole thing.

The video has a fun, special-ops feel that lets viewers in on the excitement: There are code names and walkie talkie-like communication mixed in with shots from multiple hidden cameras on the ground and in buildings along the route. Cushman, who moonlights at Unrendered Films as a developer and director when he's not working as a web programmer and appellate attorney, coordinated the plan. His brothers prepped the crowd at the ICA. Pender-Cudlip led the team of four cameramen (including one stationed on the 14th floor of a nearby high-rise), directed the video, and then stayed up all night editing it so that the couple's parents could watch the proposal play out online the next morning.

Cushman was outfitted with not one, but two microphones -- a wireless one taped to his chest, and backup that fed into a recording device in his pocket, Pender-Cudlip says -- and the guys enlisted friends at Elsey's office to let them know when she left the building.

"We had someone tail her with a GPS, and had them take video of her and coordinate with flower-givers along the route," Pender-Cudlip says.

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She turned down the first stranger who offered her a flower, but accepted a few others as she walked with Cushman to the museum, about a mile away. "Teresa guessed that the flowers might be some kind of fraternity stunt or something," Cushman wrote in his essay. "She still didn't know I had anything to do with it."

As they got closer to the museum, nearly everyone they passed had a flower for her, and when they got to the ICA, where a free concert was in progress, "she was instantly surrounded with friendly people offering her flowers," Cushman writes.

By the time the crowd of finished handing her carnations, Elsey's arms were overflowing with flowers. Cushman slipped away during the commotion to hustle into a tuxedo -- he'd cut it up and velcro'd it back together earlier in the week, to make for a quick clothing change -- and then led her to a nearby bench, kneeled in front of her with a microphone, and asked: "Teresa Elsey… would you marry me?"

"Of course!" She replied, beaming. The crowd cheered.

"After the proposal I had planned to whisk her away, because she's the kind of person who would want privacy after something like that. So we made our grand exit," Cushman writes in his essay. "The video kindly cuts out before I realized we were walking the wrong way and we snuck back through the cafe."

"We got into a waiting car out front and went out to a wonderful, hours-long dinner, where we mostly just kept staring at each other and laughing in disbelief," he continues. "When we got home, my co-conspirators had wound Christmas lights and flowers around the spiral staircase leading up to our bedroom. We found out later that they were hiding behind a tree when the cab pulled up to drop us off."

Cushman credits a team of more than 30 friends and businesses for helping him pull off his over-the-top proposal. (They also gathered sweet marriage-proposal stories from other people in the crowd; you can watch those videos here.)

"The engagement itself has brought us joy beyond words," Cushman writes. "But it's also been such a gift to share our joy with family members and friends and strangers -- to know that other people are joining us in that moment, and somehow believing in the crazy project we're undertaking. It feels like something we'll have to spend our lives living up to."

Copyright © 2012 Yahoo Inc.

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