Jaws dropped as Ashley and Jacob did the unexpected among 70,000 Metallica fans

Tens of thousands of metalheads recently descended on Accor Stadium for Metallica's first Sydney show in 12 years – two of them with a particularly unique night ahead of them.

While the heavy metal band prepared backstage and concert-goers, wearing graphic tees and leather jackets, made a pre-show dash to the bar, one couple stood hand-in-hand amongst the crowd and vowed to love each other for the rest of their lives.

Jaws dropped as those around them slowly realised what was happening right there in the mosh pit.

Watch the video above.

Ashley and Jacob MacMillan "never really wanted a big wedding," they tell nine.com.au.

Little did they know they would end up having one with a guest list of approximately 70,000 people at the concert of one of the biggest bands in the world.

The NSW-based couple originally thought about eloping somewhere on the Central Coast, then they remembered they had booked tickets to Metallica – their favourite band. 

"We wanted to elope, we just weren't sure how to do it," Ashley says. 

"And then we were like, 'Well we already have tickets to Metallica, we have leave off work, we have accommodation already booked. Why not see if we can do it there?'"

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So, with the help of their very passionate wedding celebrant Mel Roszko, who just so happened to have her own ticket to the concert, they got to planning their heavy metal wedding.

Roszko got in contact with organisers at Accor Stadium to get logistics underway and, before they knew it, Ashley and Jacob's wedding day was upon them. 

After squaring away some legal requirements with Roszko before the concert, Ashley, dressed in a white dress and Converse sneakers, and Jacob, in a Metallica singlet, walked into Accor Stadium as they would for any old concert. 

They stood in the merch line and bought some churros before heading towards the mosh pit – no one around them would have had a clue about what was to come next.

That was until they turned to each other, stood hand-in-hand and got married. 

Surrounding concert-goers stopped in their tracks to watch, jaws dropped, as Roszko officiated the three-minute ceremony in the mosh pit, just moments before the band was set to take to the stage. 

Seeing the shock on people's faces as they realised what was happening "was pretty funny", Jacob says.

"I don't think people expected it. People were curious as to what was happening and when Mel said, 'This is a wedding', they were like 'Oh wow'," he says.

Once the ceremony was over, "there were lots of hugs, lots of congratulations" and Roszko had the crowd cheer "husband and wife" before they turned their attention to the stage. 

"[Roszkol] went her way, we went our way and then Metallica started playing," Ashley says.

Since meeting on Snapchat a year and a half ago, the pair have been to their fair share of concerts together. They even got engaged at Sydney music festival Field Day at the beginning of the year. 

But it all pales in comparison to the magic of that Metallica concert.

"It would have to be the best concert that I've ever been to," Jacob says. 

"Same, hands down," Ashley agrees.

And perhaps the excited glow of their fresh nuptials had a little bit to do with that. 

Overall, it was the perfect setting for the low-key, no-frills wedding that Jacob and Ashley always wanted. 

"It was really nice, something different, stress-free and relatively cheap," Ashley says.

"We had a wedding venue, we had accommodation, we had about 70,000 guests and didn't have to feed them or buy them alcohol," she adds, with a laugh.

But it wasn't just a dream wedding for Ashley and Jacob. It was also a dream come true for Roszko. 

As we speak, she is "still buzzing" with excitement from the wedding she was able to pull off for the couple. 

"It's something I've always wanted to do, marry a couple at a concert," she tells nine.com.au.

"I'm getting goosebumps just thinking about it". 

Later, Roszko shared a video of the wedding to her Instagram and, while many praised the unique wedding, some weren't so positive with one person in the comments adamant that it wasn't a real wedding, she explains. 

"I beg to differ because we were in a venue, we had catering – there were hot chips – there was entertainment," Roszko says. 

"All you need to make a wedding is a celebrant, two people who want to get married and two witnesses over 18. So it was definitely a wedding."

And even though Roszko has officiated a lot of "quirky weddings" throughout her career as a wedding celebrant, from high up on a mountain to on a cruise ship, she says this is "definitely the most unique one [she's] ever done".

"I'm not sure you can top that," she admits.

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