A woman made a horrible faux pas at a friend's wedding when she cut into the bride and groom's untouched wedding cake.

Going viral on TikTok, wedding guest Hailey shared a video clip that shows her walking up her friend's cake during the reception, grabbing a knife and slicing into the pristine white confection, complete with bride and groom toppers.

After putting a slice on her plate, she licks frosting off her fingers.

"My apologies to the bride & groom," she captioned the clip.

According to the video, Hailey was unaware of her mistake at the time, as she simply thought the cake had already been served.

"Ignoring the brownie table and confidently cutting myself a slice of HER WEDDING CAKE thinking uh-oh! They forgot to serve it to everyone else!" Hailey shared in a text overlay, adding, "I know better now, I hate myself!"

Watch below:

The video quickly went viral, amassing nearly 4 million views and hundreds of comments since it was shared on Tuesday (August 16).

One comment came from the bride herself, who reassured viewers the pair are still on good terms.

"As the bride whose cake this is ... she is formally forgiven and has learned her lesson in wedding etiquette," the woman commented.

Nevertheless, the viral TikTok drew divisive comments.

“Did you lose your mind? I hope you found it,” one user wrote.

"Why did this person just record you doing that instead of telling you not to?” someone else asked.

"Friends are way more valuable than cake. It would take me two seconds to forgive this," another person offered.

Many facets of wedding etiquette have long been debated, however, slicing into an untouched wedding cake seems like a general no-no across the board. In many cases, the bride and groom will even save their tiered wedding cake while serving guests slices from a sheet cake of the same flavor instead.

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