New Showtime Challenges that were previously leaked have now been added to Fortnite.
In the v7.30 update, data-miners had found many files relating to the artist DJ Marshmello and it had been teased by his management that there would be a collaboration with Fortnite and the artist soon. With the weekly challenges that were released today, there were also new challenges that appeared, the Showtime Challenges, as can be see below:

There are three challenges for players to complete, but only one has been unlocked:
Here are the locations of the Showtime posters.
Players are only required to search one Showtime Poster, which is very easy to complete. The Showtime Poster can be seen below:

There will be an event on February 2nd at 2PM ET, which will take place in Pleasant Park. Marshmello has also added Pleasant Park to his touring dates.

Once players have completed the challenge, they will awarded with a Marshmello Spray, called Mello Made it Right, which had been previously leaked. You can see the spray below:

The other two challenges show they will be unlocking in 24 hours. You will be able to unlock the Keep it Mello emote and the Marshy Smasher pickaxe (harvesting tool) for completing the next two challenges. Once you have completed all three challenges, you will be awarded with a banner.