Not A Laughing Matter! Man's 'I Cheated' Prank Goes Sour When Girlfriend Admits She's Been Unfaithful Too

#1 Beaten at his own game: YouTube prankster Roman Atwood, left, decided to tell his girlfriend that he cheated while they vacationed in Aruba for the 5-year anniversary

What better way to celebrate your five-year anniversary than by fooling your girlfriend into believing you've cheated?

Professional YouTube prankster Roman Atwood did just that while he and his partner Britney vacationed in Aruba, thinking the stunt could live among his many others posted online.

But Atwood was in for the shock of his pranking career when his sobbing girlfriend admitted she'd been unfaithful, too.

#2 Pranked: With a hidden camera rolling, Atwood tells his girlfriend Britney that he cheated, even though he hasn't

#3 Happier times: Here, Roman and Brittney show their love for one another. Their trip to Aruba marked their five year anniversary

#4 'We had a family': The seemingly heartbroken Britney breaks down in sobs as Atwood begs for forgiveness

‘I'm in Aruba right now celebrating my five-year anniversary with my girlfriend,' Atwood tells the camera as he approaches their hotel room. ‘I'm going to prank her tonight by telling her I cheated on her.'

On his YouTube channel, Atwood has posted similarly tasteful prank videos such as ‘Scary Hangman Prank!' and ‘Homeless Pizza Party Prank!!!'

#5 But then...: Through her tears, Britney admits 'I cheated on you'

But he may have gone wrong with this particular stunt by involving his girlfriend.

‘We have a family,' she sobs after Atwood's fake admission.

#6 Flip out: The shocked Atwood can't believe his ears and he begs Britney to say it ain't so

#7 Gotcha! Then Britney serves her just desserts. She was pranking the prankster. 'I saw you set up your camera, you idiot!'

He says he'll never do it again and apologizes profusely. But then the tables turn.

‘I cheated on you,' Britney admits.

Atwood flips out and paces in stunned disbelief. His prank has gone terribly wrong.

Most of Atwood's jokes end with a laugh. But most don't involve Brittney.

A few tense moments appeared to put a damper on what had been a wildly popular YouTube prank career for Roman.

Then, before his anger can go too far, Britney smiles.

#8 Here is the video of the prank

She was pranking him. ‘I saw you set up your camera, you idiot!'

All is well again and both get a good laugh before Atwood wonders what's become of his prank.

‘I suck soI cannot upload that.'

Thankfully, he decided to upload it after all and the world has enjoyed it. In less than a day, the video had gained over 630,000 views.

But there may be more shenanigans in store for the serial trickster and his sly girlfriend, who admits at the end of the video: 'I thought you were going to propose!'

YouTube viewers and Twitter users are now demanding that after his cruel prank he should make good by popping the question.

'She wants to marry you bro marry her!!!!!!!!!!!!!!!!!!!' wrote commenter madman2436.