Dakota Johnson has confirmed that she once sent gorilla poop to a friend's ex-boyfriend.

The How To Be Single actress revealed that she once sent a gallon of gorilla faeces to a man who had broken her friend's heart.

Dakota shared the surprising confession during an interview for Vanity Fair's lie detector test series on YouTube.

During the segment, the Madame Web actress was asked about her loyalty to her close friends, prompting her to declare that she would be willing to lie to the police to protect her long-time friend and fellow actress, Riley Keough.

The questioning then turned to a more unusual rumour, and Dakota was asked to confirm whether or not she had once sent a gallon of gorilla faeces to a man who had wronged her friend.

"I mean, there's no way that he would watch this, so, yes, I did do that," the star replied, before clarifying, "And it's been quite a while. It's been some years."

When asked how she had managed such an unusual delivery, the Fifty Shades of Grey star explained that she had used a website called S**tSenders.com.

"You can order any kind, any size," the 35-year-old said of the site.

She was then asked if it was true that she knew where to buy pubic lice online, which prompted a laugh from the star.

When asked if she had ever made that type of purchase, Dakota quickly responded, "No! Good Lord, I'm not a monster."