A Pennsylvania couple exchanged vows four months ago, but after just receiving their wedding photos they realized their big day had been crashed in a big way.

Hollywood glamorized the art of crashing weddings in the 2005 film staring Vince Vaughn and Owen Wilson. But Krista Lamlin and Andrew Reilly were very upset when they learned a mystery couple had essentially taken over their wedding. (Via New Line Cinema / "Wedding Crashers")

REPORTER: "All they could remember was wondering who was this couple drinking their free booze, partying it up on the dance floor."

LAMLIN: "Nobody had known them. So we decided they were wedding crashers." (Via ABC)

The unidentified crashers can be seen throughout Lamlin and Reilly's wedding video, mostly dancing the night away with free drinks in hand. They were also featured in photos taken by the professional photographer at the reception.

Lamlin's mother, told WPVI that no one noticed the crashers at first because, "They were dressed to go. ... They blended right in." (Via WPVI)

REPORTER: "Eventually, the wedding planner escorted them out of the reception."

LAMLIN: "I think it's tacky. I think it's rude, because that's someone's special day and you're impeding on it." (Via WPVI)

Frustrated to see wedding crashers in her daughter's photos, Suzanne posted a photo of the couple from the wedding on WPVI's Facebook page, asking if anyone knew who they were. (Via Facebook / 6abc Action News)

The mystery crashers saw the post and got in touch with Lamlin to apologize.

A writer for New York Daily News notes the unidentified crashers told Lamlin they were guests at the resort where the reception took place and decided to join in.

Now an expert on wedding crashers, Lamlin advises all brides to keep an eye on their dance floor, telling WPVI that she never would have noticed the crashers if they'd just hung around in the background.