Failure to solve a riddle being shared on Facebook forced thousands of users to change their profile pictures to an image of a giraffe, Metro reported Monday.

The riddle is confusing many as it spreads around the social network. The question asked in the challenge is: "It's 3am, the doorbell rings and you wake up. Unexpected visitors! It's your parents and they are here for breakfast. You have strawberry jam, honey, wine, bread and cheese. What is the first thing you open?'"

(See the bottom of this article for the correct answer).

Someone posts the riddle on Facebook, challenging their friends to answer it in a private message. If the person gets it right, he or she keeps the same profile picture. Facebook users who have failed the challenge must change their profile pictures on the website to a photo of a giraffe and re-post the riddle, asking friends to message them with the answer.

If they also incorrectly guess the solution, they must change their profile picture and post the riddle for their friends to guess.

It is unclear how the game started but it is not being called a virus or scam.

A similar trend was noticed on Facebook in 2010 when users changed their profile picture to their favorite cartoon character, according to The Telegraph. It was later revealed to be part of a protest to support children.

Do not look below if you don't want the riddle ruined:

'You open the door first' and 'you open your eyes first' have both been accepted as answers by those posing the riddles on Facebook.